1988 was when it was first introduced
Final answer:
DNA evidence was first introduced in 1988 and has since revolutionized forensic science. Its discovery by Miescher in 1869 and subsequent research paved the way for its pivotal role in modern biology and criminal justice.
Explanation:
DNA evidence was first introduced in 1988. This introduction of DNA for forensic purposes marked a monumental advancement in the field of criminal investigations and legal proceedings. The science of DNA was discovered by Friedrich Miescher in 1869, and significant developments unfolded over the years, leading to our contemporary understanding of DNA as the genetic material responsible for heredity. Experiments by scientists such as Oswald Avery, Colin MacLeod, and Maclyn McCarty in the 1940s, and the discovery of the 3D-double-helix structure by James Watson and Francis Crick in 1953, set the stage for the many applications of DNA science we see today, including forensic analysis.
What are the answers to these questions and why?
Answer:
Explanation:
Here are the ones I'm certain of.
10, Transfer of electrons occurs in NaCl. That's another way of saying that the bond is ionic.
12. What is a polar molecule. The two hydrogens are + and the Oxygen is minus.
9. Contains just one sigma bond. H2 is made up of only 1 bond type. I'd pick this, but It's not certain.
=============
The one I'm uncertain of is 11. I'd pick E but it is a pure guess. The only other choice is CO2 but I don't think CO2 is that way. You'll have to enter the answers to find out which is which.
What is the molar concentration of [H3O+] in a cola that has a pH of 3.120?
The molar concentration of [H3O+] in a cola with a pH of 3.120 is approximately 7.92 x 10^(-4) M.
Explanation:The molar concentration of [H3O+] in a cola with a pH of 3.120 can be determined using the equation:
pH = -log[H3O+]
First, we need to convert the pH to a hydronium ion concentration. Using the given pH of 3.120, we can rearrange the equation and solve for [H3O+]:
[H3O+] = 10^(-pH)
Plugging in the pH value, we get:
[H3O+] = 10^(-3.120)
Calculating this, we find that the molar concentration of [H3O+] in the cola is approximately 7.92 x 10^(-4) M.
Name two lab tools used to measure the volume of a liquid
Answer:
beaker and flasks
Explanation:
What does the prefix cis- mean in chemistry
Answer:
this
Explanation:
a prefix meaning “with,” “together,” “in association,” and (with intensive force) “completely,” occurring in loanwords from Latin ( commit ): used in the formation of compound words before b, p, m: combine; compare; commingle.
In chemistry, the 'cis-' prefix indicates that two substituents are positioned on the same side of a double bond or ring structure, significantly impacting the compound's properties, as seen with cis-platin in cancer treatment.
Explanation:In chemistry, the prefix cis- refers to molecules where two substituents are on the same side of a double bond or a ring structure. Cis/trans isomerism is an important concept where the arrangement of atoms can greatly affect the physical and biological properties of a compound. For instance, in cycloalkanes, a cis configuration has both groups oriented in the same direction, which is different from the trans configuration where groups are on opposite sides. An example of this significance in biology is the drug cis-platin, which is used in the treatment of ovarian and testicular cancers due to its ability to bind to DNA and inhibit replication.
Additionally, cis/trans isomerism can also be referred to as Z/E isomerism based on Cahn, Ingold, and Prelog's priority rules. While both cis and trans compounds share similar qualities, their different spatial arrangements result in distinct characteristics.
Question 1 (1 point)
In this analogy, adding more students is analogous to:
Question 1 options:
Decreasing the volume of the reaction container.
Adding more particles of reactants.
Adding a chemical catalyst.
Increasing the temperature of the reaction.
Question 2 (1 point)
In this analogy, shrinking the hallways is analogous to:
Question 2 options:
Decreasing the volume of the reaction container.
Adding more particles of reactants.
Adding a chemical catalyst.
Increasing the temperature of the reaction.
Question 3 (1 point)
chemical catalyst helps change the rate of a chemical reaction by
Question 3 options:
Adding more reactants
Decreasing the activation energy
Increasing the activation energy
Adding more products
Question 4 (1 point)
In this analogy, shortening the passing periods is analogous to:
Question 4 options:
Decreasing the volume of the reaction container.
Adding more particles of reactants.
Adding a chemical catalyst.
Increasing the temperature of the reaction.
Question 5 (1 point)
In this analogy, hiring a matchmaker is analogous to:
Question 5 options:
Decreasing the volume of the reaction container.
Adding more particles of reactants.
Adding a chemical catalyst.
Increasing the temperature of the reaction.
Question 6 (1 point)
What are two conditions that must be met in order for a chemical reaction to take place?
Question 6 options:
Collisions with the proper orientation
Sufficient activation energy
Appropriate coefficient of friction
Both A and B
Both B and C
Answer:D - adding a catalyst
Explanation:
In this analogy, adding more students is analogous to adding more particles of reactants in a chemical reaction. Shrinking the hallways is analogous to decreasing the volume of the reaction container. A chemical catalyst helps change the rate of a chemical reaction by decreasing the activation energy.
Explanation:Question 1: Adding more students in this analogy is analogous to adding more particles of reactants in a chemical reaction. Just like adding more students can increase the amount of activity and interactions in a classroom, adding more particles of reactants can increase the collision frequency and hence the reaction rate.
Question 2: Shrinking the hallways in this analogy is analogous to decreasing the volume of the reaction container in a chemical reaction. Just like shrinking the hallways restricts the movement of students, decreasing the volume of the reaction container restricts the movement of particles and increases the collision frequency.
Question 3: A chemical catalyst helps change the rate of a chemical reaction by decreasing the activation energy required for the reaction to occur. It provides an alternate reaction pathway with a lower activation energy, allowing more particles to have sufficient energy to react.
Question 4: Shortening the passing periods in this analogy is analogous to increasing the temperature of the reaction in a chemical reaction. Just like shortening the passing periods allows students to move faster and increases their chances of colliding, increasing the temperature of the reaction increases the kinetic energy of particles and enhances their collision frequency.
Question 5: Hiring a matchmaker in this analogy is analogous to adding a chemical catalyst in a chemical reaction. Just as a matchmaker facilitates the meeting of compatible people, a chemical catalyst facilitates the reaction between reactant particles, increasing the reaction rate.
Question 6: Two conditions that must be met for a chemical reaction to take place are collisions with the proper orientation and sufficient activation energy. Collisions between reactant particles must occur with the proper orientation to enable the formation of new chemical bonds, and these collisions must also have sufficient energy to overcome the activation energy barrier.
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How would you find out if the enthalpy for the two questions exothermic or endothermic?
Answer:
Explanation:
The second one is quite simple. CH4 (methane) is the main component for natural gas. It is used to heat houses in many many areas. It it heats a house, it must give off heat. It is exothermic.
The first one is much less common and hard to reason. I think it is easier to see the reverse reaction
O2 ===> 2O
O2 is a fairly stable molecule. It takes energy to break the molecules apart. That makes this reaction endothermic.
So the reaction you are given is just the opposite. It must be exothermic.
2O ===> O2 must be exothermic.
When kaolinite clay [al2(si2o5)(oh)4] is heated to a sufficiently high temperature, chemical water is driven off?
Final answer:
Heating kaolinite clay results in the removal of hydroxyl groups as water in a process known as dehydroxylation, producing metakaolin and eventually aluminum oxide (Al2O3).
Explanation:
When kaolinite clay, which has the formula Al2(Si2O5)(OH)4, is heated to a high temperature, it undergoes a process known as dehydroxylation. This process involves the removal of hydroxyl groups as water, which is referred to as 'chemical water'.
When heated sufficiently, the kaolinite loses water molecules and forms metakaolin, an intermediate phase before it eventually transforms into aluminum oxide (Al2O3), also known as alumina. Alumina is important as it is a precursor for aluminum production through the electrolysis of aluminum ions in a solution containing cryolite (Na3AlF6) and calcium fluoride (CaF2).
Any units will do. For example, let's use the unit of "dozens":
2 dozen of H2 particles + _(1, 2, or 3)__ dozen of O2 particles → _(1, 2, or 3)_ dozen water particles
Answer:
2 dozen of H₂ particles + 1 dozen of O₂ particles → 2 dozen of H₂O particles.
Explanation:
For the reaction of water formation:2H₂ + O₂ → 2H₂O.
It should apply the the law of conservation of mass that the no. of reactants atoms is equal to the no. of products atoms.
So, every 2.0 moles of H₂ react with 1.0 mole of O₂ to produce 2.0 moles of H₂O.
So, the represented reaction of the problem is:
2 dozen of H₂ particles + 1 dozen of O₂ particles → 2 dozen of H₂O particles.
Complete each sentence using the drop-down menus.
Desertification mainly impacts resources.
Point and nonpoint sources refer to types of pollution.
The process of people moving to cities, called , greatly impacts land, air, and water resources.
The burning of fossil fuels can cause .
Answer:
Desertification mainly impacts land resources.
Point and nonpoint sources refer to types of water pollution.
The process of people moving to cities, called urbanization , greatly impacts land, air, and water resources.
The burning of fossil fuels can cause smog and acid rain.
Explanation:
Desertification impacts natural resources. Point and nonpoint sources refer to types of water pollution. Urbanization has significant impacts on land, air, and water resources. The burning of fossil fuels can cause environmental pollution.
Explanation:Desertification mainly impacts natural resources. This process refers to the degradation of once fertile land into barren desert due to factors such as climate change, deforestation, and overgrazing. It can lead to the loss of agricultural productivity, water scarcity, and biodiversity decline.
Point and nonpoint sources refer to types of water pollution. Point sources are specific and identifiable sources of pollution, such as pipes discharging industrial waste into a river. Nonpoint sources are diffuse sources, such as runoff from agricultural fields, that enter water bodies indirectly.
The process of people moving to cities, called urbanization, greatly impacts land, air, and water resources. Urbanization often leads to the conversion of agricultural land into concrete jungles, increased air pollution from vehicles and industries, and increased water demand and waste generation.
The burning of fossil fuels can cause environmental pollution. When fossil fuels, such as coal, oil, and natural gas, are burned for energy production or transportation, they release pollutants like carbon dioxide, sulfur dioxide, and nitrogen oxides. These pollutants contribute to air pollution, climate change, and acid rain.
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What volume of 5.00 × 10-3 m hno3 is needed to titrate 80.00 ml of 5.00 × 10-3 m ca(oh)2 to the equivalence point? what volume of 5.00 × 10-3 m hno3 is needed to titrate 80.00 ml of 5.00 × 10-3 m ca(oh)2 to the equivalence point? 80.0 ml 160. ml 10.0 ml 40.0 ml?
Answer:
= 160 mL
Explanation:
The equation for the reaction is;
Ca(OH)2 + 2HNO3 -----> Ca(NO3)2 + 2H2O
Moles of Ca(OH)2 = 0.080 L x 5.00^-3 M
= 0.0004 moles
From the reaction; 2 moles of HNO3 reacts with 1 mole of Ca(OH)2
Thus; moles of HNO3 = 0.0004 Moles × 2
= 0.0008 moles
Volume = moles/ molarity
Therefore; volume of HNO3= 0.0008 Moles/ 5 × 10^-3 M
= 0.16 L or 160 mL
The volume of 5×10⁻³ M HNO₃ needed to titrate 80ml of 5×10⁻³ M ca(oh)2 to the equivalence point is 160mL.
How we calculate volume from moles?
Volume of any solution will be calculated by using moles and molarity as:
Volume = moles / molarity
Given chemical reaction is:
Ca(OH)₂ + 2HNO₃ → Ca(NO₃)₂ + 2H₂O
From the stoichiometry of the reaction it is clear that,
2 mole of HNO₃ = react with 1 mole of Ca(OH)₂
Given volume of Ca(OH)₂ = 80mL = 0.080L
Given molarity of Ca(OH)₂₂ = 5×10⁻³ M
Moles of Ca(OH)₂ = 0.080L x 5×10⁻³M = 0.0004 moles
0.0004 moles of Ca(OH)₂ = react with 2×0.0004 = 0.0008 moles of HNO₃
Given molarity of HNO₃ = 5×10⁻³ M
Volume of HNO₃ = 0.0008moles / 5×10⁻³ M = 0.16L = 160mL
Hence, 160mL of HNO₃ is required.
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According to periodic trend, which of the following most likely has the highest ionization energy? Be B Ne O
Answer:
Ne
Explanation:
Answer: The correct answer is Beryllium.
Explanation:
Ionization energy is defined as the energy required to remove valence electron from an isolated gaseous atom. It is expressed as [tex]E_i[/tex]
[tex]X(g)\rightarrow X^{n+}(g)+ne^-[/tex]
Energy required for a stable molecule (having fully filled and half filled electronic configuration)
The electronic configuration for the elements given are:
1. Be : [tex]1s^22s^2[/tex]
This element will have the highest ionization energy because this element has stable electronic configuration and electrons present in '2s' orbital is near to the nucleus. So, to remove this electron, we need a huge amount of energy.
2. B : [tex]1s^22s^22p^1[/tex]
This element does not have stable electronic configuration. So, this will not have highest ionization energy.
3. Ne : [tex]1s^22s^22p^6[/tex]
As, this element has stable electronic configuration but the valence electron is far from the nucleus and does not require a huge amount of energy to remove it. So, this will not have highest ionization energy.
4. O : [tex]1s^22s^22p^4[/tex]
This element does not have stable electronic configuration. So, this will not have highest ionization energy.
From the above information, we can conclude that the Beryllium has the highest ionization energy.
please compare the energies of excitation and emission for fluorescence. Which is greater and why?
Answer:
The excitation energy is always greater than the emission energy .
Explanation:
When a molecule absorbs energy, electrons are excited from the ground state (S₀) to different vibrational levels of the excited state (S₁) in about 1 fs.
In the next picosecond, most of them will drop to the lowest vibrational level of S₁.
They remain there for about 10 ns, and then they drop to different vibrational levels of S₀.
The excitation energy is always greater than the emission energy because excitation occurs from the ground state of S₀ to a higher vibrational level of S₁, while emission occurs from the lowest vibrational level of S₁ to a higher vibrational of S₀.
The excitation energy of fluorescence is greater than the emission energy.
What is excitation energy?Excitation has to do with absorption of energy by a ground state molecule in (S₀) moving it to a different vibrational levels (S₁) which is higher in about 1 fs.
It the subsequently drops in one picosecond, most of them will drop to the lowest vibrational level of S₁.
Note that excitation energy must be greater than emission energy owing to the fact that excitation begins at the ground state moving up to a higher vibrational level , while emission begins at the lowest vibrational level moving up to a higher vibrational levels.
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List your example of turning an observation into a hypothesis. Be sure to list all five steps: observation, explanation, test (independent variable), prediction (dependent variable), and hypothesis
A simple hypothesis is a prediction of the relationship between two variables: the independent variable and the dependent variable.
Drinking sugary drinks daily leads to obesity.
A complex hypothesis examines the relationship between two or more independent variables and two or more dependent variables.
Overweight adults who 1) value longevity and 2) seek happiness are more likely than other adults to 1) lose their excess weight and 2) feel a more regular sense of joy.
A null hypothesis (H0) exists when a researcher believes there is no relationship between the two variables, or there is a lack of information to state a scientific hypothesis. This is something to attempt to disprove or discredit.
There is no significant change in my health during the times when I drink green tea only or root beer only.
This is where the alternative hypothesis (H1) enters the scene. In an attempt to disprove a null hypothesis, researchers will seek to discover an alternative hypothesis.
My health improves during the times when I drink green tea only, as opposed to root beer only.
A logical hypothesis is a proposed explanation possessing limited evidence. Generally, you want to turn a logical hypothesis into an empirical hypothesis, putting your theories or postulations to the test.
Cacti experience more successful growth rates than tulips on Mars. (Until we're able to test plant growth in Mars' ground for an extended period of time, the evidence for this claim will be limited and the hypothesis will only remain logical.)
An empirical hypothesis, or working hypothesis, comes to life when a theory is being put to the test, using observation and experiment. It's no longer just an idea or notion. It's actually going through some trial and error, and perhaps changing around those independent variables.
Roses watered with liquid Vitamin B grow faster than roses watered with liquid Vitamin E. (Here, trial and error is leading to a series of findings.)
A statistical hypothesis is an examination of a portion of a population.
If you wanted to conduct a study on the life expectancy of Savannians, you would want to examine every single resident of Savannah. This is not practical. Therefore, you would conduct your research using a statistical hypothesis, or a sample of the Savannian population.
Final answer:
Turning an observation into a hypothesis involves observing a natural event, formulating a plausible explanation, testing this explanation by manipulating an independent variable, predicting the outcome on a dependent variable, and stating a hypothesis that brings all these elements together.
Explanation:
Turning an observation into a hypothesis involves several critical steps, each building upon the previous to develop a testable prediction about a natural phenomenon. Below is an example detailing this process.
Observation: Plants in a garden receiving more sunlight tend to be more vibrant and grow taller than those in shaded areas.
Explanation: Sunlight may provide energy that is essential for the growth and health of plants.
Test (Independent Variable): The amount of sunlight exposure plants receive.
Prediction (Dependent Variable): The health and growth rate of the plants.
Hypothesis: If plants are exposed to more sunlight, then they will grow taller and have a more vibrant appearance, because sunlight provides the necessary energy for photosynthesis.
This hypothesis can then be tested through experimentation, ultimately contributing to the cycle of scientific inquiry.
Equation to paragraph plzz
Answer:
AgNO₃₍aq₎₎ + NaCl ₍aq₎₎ --------> NaNO₃₍aq₎ + AgCl₍s₎
Explanation:
Silver Nitrate: AgNO₃
Sodium Chloride: NaCl
Sodium Nitrate: NaNo₃
silver(I) chloride: AgCl
Equation:
AgNO₃₍aq₎₎ + NaCl ₍aq₎₎ --------> NaNO₃₍aq₎ + AgCl₍s₎
The atomic number of a nuclide that undergoes alpha decay _____.
increases by 2
increases by 4
decreases by 2
decreases by 4
C. decreases by 2
The mass number decreases by 4, and the atomic number decreases by 2
Final answer:
The atomic number of a nuclide decreases by 2 during alpha decay due to the emission of an alpha particle, which consists of two protons and two neutrons.
Explanation:
The atomic number of a nuclide that undergoes alpha decay decreases by 2. Alpha decay is a nuclear reaction where an unstable atom emits an alpha particle, which consists of two protons and two neutrons (the same as a helium-4 nucleus). Because two protons are lost, the atomic number decreases by two.
At the same time, because a total of four nucleons (two protons and two neutrons) are lost, the mass number of the atom decreases by four.
Which of the following laws states that the volume of a gas and the amount of a gas in moles are directly proportional?
You haven't provided a list of answers but the law to which states "volume of gas is proportional to the number of moles of gas," is Avogadro's law.
What inorganic molecule is carbon normally found in?
It’s CO2
Carbon dioxide
Air resistance depends upon _____.
A. the inertia of a moving object
B. the velocity of a moving object
C. the mass of a moving object
D. the weight of a moving object
Answer:
ye its b
Explanation:
Air resistance highly depends on the velocity of a moving object. It also depends on other factors like the object's shape, size, and the fluid's density. Among the given options, velocity is the most accurate answer.
Explanation:Air resistance, often termed as drag in physics, is the force that opposes an object's motion through a fluid (either gas or liquid). The statement 'Air resistance depends upon _____.' pertains to the factors affecting the magnitude of air resistance that an object experiences. Most accurately, air resistance depends on the velocity of a moving object (Option B). This relationship is particularly evident in larger velocities, where the air resistance can increase exponentially.
Additionally, air resistance is also affected by factors such as the shape and size of the object, and the density of the fluid (air in this case). For example, a smoothly shaped, small object experiences less air resistance compared to a larger or irregularly shaped object at the same velocity.
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Identify the missing numbers for Vanadium (V) for "A, ""B," and "C" in the chart below. The first number in the answer selection represents "A", the second number in the answer selection represents "B," and the third number in the answer selection represents "C."
Answer:
The right choice is:
B. 21, 21, 53.
Explanation:
Atomic Number = Number of electrons = Number of protons
So, the No. of protons (A) = Number of electrons =21
Atomic Number (B) = Number of electrons =21
Mass number (C) = Number of electrons + Number of neutrons = 21 + 32 = 53
So, the right choice is:
B. 21, 21, 53.
A mixture of two gases was allowed to effuse from a container. one of the gases escaped from the container 1.43 times as fast as the other one. the two gases could have been:
Answer:
C. Cl2 and SF6
Explanation:
According to the Graham's law of diffusion the rate of effusion or diffusion of a fixed mass of a gas is inversely proportional to the square root of its density or mass.For two gases; R1/R2 = √mm2/√mm1 ; where R1 and R2 are the rates of diffusion of the two gases respectively, while mm1 and mm2 are the molecular masses respectively.Therefore, in this case we need two gases that have a ratio of their rates of diffusion as 1.43.
Thus; For Cl2 and SF6
Molecular mass of Cl2 is 70.906 g/mol, while that of SF6 is 146.06 g/mol
Therefore, the ratio of their rates of diffusion will be;
√(MM of SF6)/√(MM of Cl2) = √ 146.06/√70.906
= 1.4352
= 1.43
Therefore; the two gases required are Cl2 and SF6
Based on Graham's law, if one gas effuses 1.43 times as fast as another, the faster-moving gas likely has a lower molar mass. An exemplary pair could be helium and neon.
Explanation:The phenomenon of effusion is dictated by Graham's law, which states the rate of effusion of a gas is inversely proportional to the square root of the mass of its particles. If one of the gases escapes 1.43 times as fast as the other, it could be inferred that the slower-moving gas has a greater molar mass in comparison to the faster one due to an inverse relationship.
However, without specific details about the exact molar masses, it's challenging to state precisely what the gases could be. Nonetheless, in a hypothetical scenario, it could be a pair of helium and neon, where helium being lighter would effuse faster. Please remember, that this is just an illustrative example.
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Which reaction represents cellular respiration?
a.sugar + oxygen → carbon dioxide water + atp
b.carbon dioxide + water + atp → sugar + oxygen
c.oxygen + carbon dioxide → sugar + water + atp
d.water + atp → carbon dioxide + sugar?
Answer:
A.sugar + oxygen → carbon dioxide water + atp
Explanation:
Cellular respiration is a process by which cells use organic compounds such as glucose in presence of oxygen to generate energy in the form of ATP, that is used to drive cellular processes such as transport.Cellular respiration generates ATP together with carbon dioxide and water as by products. The process mainly takes place in the mitochondria also known as the power house of the cell. The process occurs in three stages, namely; glycolysis, Kreb's cycle and electron transport chain.Cellular respiration is a biological process whereby glucose (sugar) and oxygen are used to produce ATP (energy), with carbon dioxide and water as byproducts. This process consists of three main stages, Glycolysis, Krebs Cycle, and Electron Transport Chain. Thus, option A: 'sugar + oxygen → carbon dioxide + water + ATP' accurately represents cellular respiration.
Explanation:In the realm of biology, the reaction that best represents cellular respiration is option A: sugar + oxygen → carbon dioxide + water + ATP. This is because, in the process of cellular respiration, glucose (sugar) and oxygen are utilized to generate energy in the form of ATP (Adenosine Triphosphate), while releasing carbon dioxide and water as byproducts.
Cellular respiration consists of three main stages: Glycolysis, Krebs Cycle (Citric Acid Cycle), and Electron Transport Chain. During these stages, energy is extracted from glucose and used to form ATP. Oxygen acts as the final electron acceptor in the process, ultimately leading to the formation of water.
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Gases tend to deviate from the ideal gas law at
Answer:
Gases tend to deviate from ideal gas law at high pressures and low temperatures.
Explanation:
The main statements from molecular kinetic theory to describe an ideal gas is that 1) the gas particles occupy a neglictible fraction of the total volume of the gas, and 2) there is not force of attraction between gas particles.
HIgh pressure means that the gas particles will be forced closer to each other, making that the mean distance between the particles be realtively more important and their volume less neglictible. This is a violation the first assumption described above.
Since the temperature is directly related to the kinetic energy, and the latter with the movement of the particles (average speed), low temperatures lead to the molecules being less independent of each other, i.e. the forces between the molecules will count more . This fact constitutes a violation of the second principle established in the first paragraph.
In conclusion, high pressures and low temperatures tend to deviate gases from the ideal gas law.
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In an experiment to determine the acceleration due to gravity, one student holds a pencil at arm’s length and drops it. Another student starts a timer when the first student lets go and stops the timer when the pencil hits the ground. They repeat this several times and take an average. Is this a valid experiment, why or why not?
A. No, it is not valid because they are only dropping one item.
B. No, it is not valid because taking the average will increase rounding error.
C. Yes it is valid.
D. No, it is not valid because the short distance means there will be a lot of error due to the student’s reaction time.
I think it is not a valid experiment . I go with D
The experiment to determine acceleration due to gravity has potential flaws due to short drop distance and potential inconsistencies with timing due to human reaction times. A more accurate experiment would require a longer drop distance and more consistent timing method.
Explanation:The experiment described for determining the acceleration due to gravity isn't completely invalid but it is overly simplified and prone to errors. Option D is the most accurate answer - the short drop distance and potential inconsistency with the start and stop times due to human reaction could induce significant errors into the measurements. A more precise experiment would include a longer drop distance, a more consistent timing method (for example, using sensor-based stopwatch triggers), and repeated tests with different objects to make sure the results are not specific to just the pencil.
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Will give brainliest!!Given the following balanced equation: 2K + Br2 —-> 2KBr
A. List each element on the reactant side and each element on the product side and assign the correct oxidation number to each.
B. Identify which element is oxidized in the reaction and which is reduced.
C. Identify the oxidizing agent in this reaction.
A. Reactant side: K(+1), Br2(0); Product side: K(+1), Br(-1). B. Potassium is oxidized, and bromine is reduced. C. Bromine is the oxidizing agent in this reaction.
A. Let's analyze the oxidation numbers for each element in the given equation:
On the reactant side:
- Potassium (K) has an oxidation number of 0.
- Bromine (Br2) is a diatomic molecule, and its oxidation number is 0.
On the product side:
- Potassium bromide (KBr) has potassium with an oxidation number of +1, and bromine with an oxidation number of -1.
B. To determine which element is oxidized and which is reduced, compare the oxidation numbers:
- Potassium goes from an oxidation number of 0 to +1, indicating that it loses electrons and is oxidized.
- Bromine goes from an oxidation number of 0 to -1, indicating that it gains electrons and is reduced.
C. The oxidizing agent is the substance that causes another substance to be oxidized. In this reaction, bromine is the oxidizing agent because it causes potassium to lose electrons (undergo oxidation).
Final answer:
In the reaction 2K + Br2 → 2KBr, K is oxidized from an oxidation number of 0 to +1 and Br2 is reduced from 0 to -1. Br2 is the oxidizing agent as it gains electrons; K is the reducing agent as it loses electrons.
Explanation:
To answer the question about the chemical reaction 2K + Br2 → 2KBr:
Assigning oxidation numbers: Potassium (K) has an oxidation number of 0 as a pure element, and Bromine (Br2) also has an oxidation number of 0 as a diatomic molecule. In the product, potassium bromide (KBr), K has an oxidation number of +1 and Br has an oxidation number of -1.
Identifying what is oxidized and what is reduced: Potassium (K) is oxidized because its oxidation number increases from 0 to +1. Bromine (Br2) is reduced because its oxidation number decreases from 0 to -1.
Determining the oxidizing agent and reducing agent: The oxidizing agent is Bromine (Br2), because it gains electrons and is reduced to Br- ions. The reducing agent is Potassium (K), as it loses electrons and is oxidized to K+ ions.
If the concentration of H+ is 1 x 10 ^-3 M, what is the pH? Is the solution acidic, neutral or basic? Be sure to include the formula and show your work for each step in the calculation.
Answer:
[tex]\boxed{\text{3; acidic}}[/tex]
Explanation:
[H⁺] = 1 x 10⁻³ mol/L
To get the pH, you take the negative logarithm of the hydrogen ion concentration.
pH = -log[H⁺]
= -log(1 × 10⁻³)
= -log1 - log(10⁻³)
= 0 – (-3)
= 0 + 3
= 3
The pH is less than 7, so the solution is acidic.
According to pH values, the value below 7 indicates acidity. As per the given concentration of hydrogen ion, the pH value is 3 which means it is acidic.
What is the use of pH?pH is the value to determine whether the solution is acidic or basic.
It can be calculated as
[tex]pH= -log[H^{+} ][/tex]
Given,
[H⁺] = 1 x 10⁻³ mol/L
[H⁺]= -log(1 × 10⁻³)
[H⁺]= -log1 - log(10⁻³)
[H⁺]= 0 – (-3)
[H⁺]= 0 + 3
[H⁺]= 3
Thus, it can be concluded that the pH value here is 3, it means it is acidic.
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Which of the following pieces of glassware can be used to measure the volume of a liquid with the
greatest accuracy?
a. Test tube
b. Beaker
c. Flask
d. Graduated cylinder
Answer:
The correct option is GRADUATED CYLINDER.
Explanation:
Each of the glassware used in the laboratory has its specific functions. The graduated cylinder is especially manufacture to facilitate the measurement of accurate volume of liquids in the laboratory. Measurements obtained by means of graduated cylinder can be considered to be moderately accurate; volumentric flasks are more accurate than graduated cylinder and should be used when higher precision are required.
The most accurate piece of glassware to measure the volume of a liquid is a graduated cylinder, due to its precise measurement markings. Other forms of glassware like test tubes, beakers, and flasks can also measure volume, but with less accuracy.
Explanation:The piece of glassware used to measure the volume of a liquid with the greatest accuracy among the given options is a graduated cylinder. Test tubes, beakers, and flasks provide approximate measurements, but for higher accuracy, a graduated cylinder is used. This is due to the precise measurements inscribed on the surface of the cylinder. Graduated cylinders are typically used in scientific experiments where accuracy is crucial for obtaining reliable and valid results.
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___________ is a comfortable number of guests for an evening of good conversation.
Ten or less
Ten to twelve
Thirteen to fifteen
Answer: 10 or less
Explanation: The reason it should be ten or less is because having to many people can make you feel uncomfortable. So you want to stick with a big group but not that big of a group.
Ten or less is a comfortable number of guests for an evening of good conversation.
Explanation:Usually people visit their neighbors or go as guest to their relative houses during evening time. It is because evening is the exact time during which all the members of the family will be present at home. Some people like to converse with each other.
The best count for comfortable evening conversation may be ten or less. It is considered as best because; if a guest is visiting our house we need to provide hospitality to them by serving something to eat and to provide space to sit. If the count goes above 10, it will become crowded and will cause problem in hospitality and will not pave wave for good conversation.
Estimate the optimal number of neutrons for a nucleus containing 70 protons.
Atomic number 70
weight 173
number of neutron = weight - Atomic number
= 173 -70
=103
The optimal number of neutrons for a nucleus containing 70 protons is 130
Further explanationIn chemistry, the nucleus is the positively charged center of the atom that consist of protons and neutrons. It's also known as the "atomic nucleus"
The neutron is a subatomic particle with no net electric charge and a mass slightly greater than that of a proton. The neutron is have symbol n or n⁰. Protons and neutrons constitute the nuclei of atoms.
Neutron is a type of atomic particle which does not possess any kind of charge on it. It has neutral behavior toward atoms since it does not possess any kind of charges but it contributes to the mass of the atoms.
Atomic number = 70
Atomic weight = 173
Atomic weight = number of protons + number of neutrons
Atomic number = number of protons
Therefore, the number of protons = 70
Number of neutrons = atomic weight - number of protons
Number of neutrons = 173 - 70 = 103
Optimal number of neutrons = 130
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Grade: 9
Subject: chemistry
Chapter: the optimal number of neutrons
Keywords: protons, nucleus, neutrons
Which of the following molecules has only single bonds?
a. CH2CH2
b. CH3CH3
c. CO2
d. CHCH
Answer:
C
Explanation:
it only bonded with one other molecule carbon/ oxgen=carbon dioxide
b. CH3CH3(Ethane) is the only molecule in the following that has only single bonds.
What are chemical bonds?Chemical bonds are defined as the connection between two atoms or the strong force of attraction that is binding the two atoms which are the result of sharing of electrons.
There are many types of bonds namely: covalent bonds, hydrogen bonds, ionic bonds, metallic bonds, etcThe bond between 2 carbon atoms is always a covalent bond meaning sharing of electrons.A covalent bond can be either a single bond, double bond or triple bond. The structure of ethane only has a single bond.Hence option a. is the right option.
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What type of functional group is represented in the compound?
The indicated group is a NH group bonded to a central atom by a single bond.
Amine
Alkene
Inorganic compound
Alkyne
Answer:
Amine
Explanation:
This functional group is that of amines. Specifically a secondary amine. It is called an N-subsituted amino group.
Here, two Hydrogen atoms of ammonia have been replaced by alkyl and/or aryl groups. The functional group of this class of amines is -NHR (N-alkylamino or N-arylamino group).
The amines shows considerable basicity.
Answer:
amine
Explanation: