The correct answer is "The crystals did not phosphoresce within the drawer but did expose the film."
Becquerel is credited to have discovered radioactivity. Becquerel was studying the properties of x-ray using naturally fluorescent minerals. Uranium shows radioactive decay. It is the high energy invisible radiation from uranium that exposed the photographic film.
This graph shows the concentration of the reactant A in the reaction A→B.
Determine the average rate of the reaction between 0 and 10 seconds.
0.007 M/s
0.014 M/s
0.86 M/s
0.07 M/s
Answer:
0.014 M/s
Explanation:
The rate of a reaction depends on the concentration of a particular compound and it stoichmetry coefficient. For the reaction:
aA + bB → cC +dD
The rate can be calculated:
r = -(1/a)xΔ[A]/Δt = -(1/b)xΔ[B]/Δt = (1/c)xΔ[C]/Δt = (1/d)xΔD/Δt
The minus signal for the reagents its because they are being consumed, so Δ[A] and Δ[B] will be negative, and r must be positive. Δt is the time variation.
So, for the reaction given, in t = 0, [A] =1 M, and in t= 10s, [A] = 0.86 M, then
Δ[A] = -0.14 M
r = -(Δ[A]/Δt)
r = -(-0.14/10)
r = 0.014 M/s
Although Thomas was sitting right next to his friends in the park, he was able to smell buttered popcorn a couple of minutes before they did. He has a lower __________ for smells than his friends.
Although Thomas was sitting right next to his friends in the park, he was able to smell buttered popcorn a couple of minutes before they did. He has a lower absolute threshold for smells than his friends.
What is absolute threshold?Absolute threshold is defined as the minimum amount of stimulation required to trigger the sensation of touch, taste, smell, vision or hearing.
It can also be defined as the smallest amount of a stimulus that a person can detect half a time. It is the part of neuroscience.
Thus, although Thomas was sitting right next to his friends in the park, he was able to smell buttered popcorn a couple of minutes before they did. He has a lower absolute threshold for smells than his friends.
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Select the equations that are correctly balanced.
a. H2O + 2O2 → H2O2
b. Fe2O3 + 3H2 → 2Fe + 3H2O
c. Al + 3Br2 → AlBr3
d. CaCO3 → CaO + CO2
Answer:
b & d are correctly balanced. Hope this helped!
Explanation:
The 64.8-g sample of the compound X2O5 contains 48.0 g of oxygen atoms. What is the molar mass of element X?
write the equation, Aluminum metal reacts with oxygen gas to produce aluminum oxide solid.
A box experiences a 20 N force to the left and two different 8 N forces to the right.(A) Will accelerate to the left (B) Will accelerate to the right (C) Will not accelerate
The greater force will dominate here and the object will accelerate to the left. The net force acting on the object will be 2 N .
What is force ?Force is an external agent acting on an object to change its state of motion or rest or to deform it. There are various kinds of forces such as gravitational force, magnetic force, nuclear force etc.
According to Newton's second law of motion, force is the product of mass and acceleration. If two same or different forces acting from the same direction, they will add up together. If two forces acting from opposite direction, they will balance each other in magnitude.
Here, 20 N acts to the right and total 16 N acts to the left. Hence, 2 N net force acts to the left. Then, the box will accelerate to the left side. Hence, option B is correct.
Find more on force:
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As the concentration of a given salt solution increases, the conductivity of the solution:
a) increases
b) no way to predict
c) remains the same
d) increases then decreases
decreases ...?
Answer: Option (a) is the correct answer.
Explanation:
Conductivity of a solution depends number of ions present in the solution. As these ions move from one place to another and thus there will be easily flow of current.
So, when there is increase in concentration then it means there are moer number of ions present into the solution.
Thus, conductivity will also increase due to increase in concentration of salt solution.
The Periodic Table of Elements is organized by the number of:
Calculate the Cal(kcal) in 1 cup of whole milk: 12 g of carbohydrate, 9 g of fat, and 9 g of protein.
Answer:
165Kcal in a cup of whole milk
Explanation:
Hello! Let's solve this!
We know that 1g
carbohydrate = 4 Kcal
1g protein = 4Kcal
1g fat = 9Kcal
We do the conversion of each one
carbohydrates = 12g * 4Kcal * g = 48Kcal
Proteins = 9g * 4Kcal / g = 36Kcal
fat = 9g * 9Kcal / g = 81Kcal
We add all the results to have the total Kcal
48Kcal + 36Kcal + 81Kcal = 165Kcal in a cup of whole milk
what property do atoms of these elements have that helps make the molecules polar
Tracem-p outlines potential hazards and mechanisms of injury at a hazardous materials (hazmat) incident. the letter “t” stands for:
Which type of atom has the strongest attraction for electrons in bond formation? barium (Ba) chlorine (Cl) iodine (I) strontium (Sr)
Answer: Chlorine has the strongest attraction for electrons in bond formation.
Explanation:
Chlorine is highly electronegative as compared to iodine and has high electron gain enthalpy. So, it will readily accept an electron in order to complete its octet. The electronegativity decreases down the group from Cl to I, and hence the tendency to gain an electron decreases.
In case of Barium, and Strontium there are completely filled sub shells and therefore the tendency to gain an electron is the least.
Thus, it can be concluded that chlorine has the strongest attraction for electrons in bond formation.
In a flame test experiment, Sodium gives the brightest and most persistent colour in the flame. Do you think that Potassium could be detected visually in the presence of Sodium, by heating this mixture in a flame? Explain your answer.
Yes, it is possible to visually detect the presence of potassium, even though sodium produces a brighter and more persistent color.
In a flame test experiment, the color observed in the flame is due to the excitation and subsequent relaxation of electrons in atoms or ions.
Each element has a unique set of energy levels, and when the electrons transition between these levels, they emit light of specific wavelengths, which we perceive as colors.
To enhance the visibility of potassium's flame color, one could adjust the experimental conditions, such as using a higher concentration of potassium or reducing the concentration of sodium.
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Final answer:
Potassium can be detected in the presence of sodium during a flame test by looking for its characteristic lilac color. Special equipment like spectrometers can enhance the detection of potassium's color in the flame test.
Explanation:
In a flame test experiment, when sodium is present, it can overwhelm other colors due to its bright yellow flame, which is highly persistent and intense. However, potassium can still be detected visually in the presence of sodium in a flame test. Potassium imparts a lilac color to the flame, which can be observed at the moment when the sodium's yellow emission fades, or by observing the edge of the flame where the color may be less intense. Additionally, the use of spectrometers or filters can help in better visualizing the potassium flame in the presence of sodium.
what is the law of conservation of mass? how is it related to balancing chemical equations
Which of the following substance is not an acid?
Substance A is tested and found to have a pH of 3.
Substance B, a common food, tastes sour.
Substance C causes metals to corrode.
Substance D feels slippery in solution.
an ore contains a mixture of zinc carbonate and lead carbonate. Zinc and lead are produced from this ore by 2 reactions.
REACTION 1: The carbonates in the ore are converted into a mixture of zinc oxide and lead oxide
Name this type of reaction. ______________________
How is this reaction done? _______________________
REACTION 2: the metals are mixed with carbon and heated in a furnace to produce zinc and lead
Explain why zinc and lead are produced ...?
Answer: the ore undergoes a decomposition reaction to convert the carbonates into metal oxides, and then a reduction reaction to produce the pure metals zinc and lead.
Explanation:
The type of reaction in which the carbonates in the ore are converted into a mixture of zinc oxide and lead oxide is called a decomposition reaction.
In this reaction, the zinc carbonate and lead carbonate compounds are broken down into their respective metal oxides, zinc oxide and lead oxide. This is achieved by heating the ore, which provides the energy needed to break the chemical bonds in the carbonates.
The decomposition reaction is represented by the following chemical equation:
ZnCO3 (zinc carbonate) → ZnO (zinc oxide) + CO2 (carbon dioxide)
PbCO3 (lead carbonate) → PbO (lead oxide) + CO2 (carbon dioxide)
The second reaction, known as reduction, involves mixing the metal oxides (zinc oxide and lead oxide) with carbon and heating them in a furnace. This process is known as smelting.
During smelting, the carbon acts as a reducing agent, meaning it removes the oxygen from the metal oxides. This reduction reaction converts the metal oxides into their respective pure metals, zinc and lead. The carbon combines with oxygen to form carbon dioxide.
The reduction reaction can be represented by the following chemical equation:
ZnO (zinc oxide) + C (carbon) → Zn (zinc) + CO (carbon monoxide)
PbO (lead oxide) + C (carbon) → Pb (lead) + CO (carbon monoxide)
Zinc and lead are produced because the smelting process separates the metal atoms from the oxygen atoms in the metal oxides. This is possible because carbon has a higher affinity for oxygen than zinc and lead do. As a result, the carbon reacts with the oxygen, leaving behind the pure metals.
On a graph, which type of line shows a direct proportion? A. upwardly curved line B. downwardly curved line C. straight line D.jagged line
Answer: Straight line
Explanation:
A straight line on the graph shows two factor that are represented on the x-axis and y-axis is directly proportional to each other.
In this condition the graph between these terms is a straight line. The term directly proportional states that if one factor is increasing then the other factor will also increase.
Example : Ohm's law, a straight line is formed when a graph is made between voltage and current as V=IR
Hence, the correct answer is option C
The maximum number of orbits in an atom is _____.
-three
-five
-seven
-nine
Suppose you wanted to calculate the heat of reaction for the formation of ammonia gas and gaseous hydrochloric acid from solid ammonium chloride.
a. Write a balanced equation for this reaction.
Answer:
Above is correct, but the heat of reaction is 176.18 J/mol
Explanation:
1) The spectrum of lithium has a red line of 670.8 nanometers. (Remember 1 m = 1 X 109 nm) a. Convert the nanometer to meter using dimensional analysis. b. Calculate the frequency of the wave. c. Calculate the energy of a photon with this wavelength.
Give the electron configuration for a neutral atom of manganese. Atomic number of Mn is 25.
1.Which best explains why ionization energy tends to decrease from the top to the bottom of a group?
A.The number of orbitals decreases.
B.The number of neutrons decreases.
C.Electrons get closer to the nucleus.
D.Electrons get farther from the nucleus.
3.When electrons are removed from the outermost shell of a calcium atom, the atom becomes
A. an anion that has a larger radius than the atom.
B. an anion that has a smaller radius than the atom.
C. a cation that has a larger radius than the atom.
D. a cation that has a smaller radius than the atom.
Answer:
1) Electrons get farther from the nucleus.
2) a cation that has a smaller radius than the atom.
Explanation:
1) ionization energy is the energy required to remove the valence electron from an isolated gaseous atom of an element.
Thus it requires some energy to remove the electron as electrons are attracted towards nucleus (positive protons are present) due to nuclear charge.
As the size increases on moving top to bottom (due to more number of shells) the distance of electrons from the nucleus increases which decreases the effective nuclear charge on electrons, decreasing the ionization energy.
2) When an atom loses an electron it attains a positive charge and is known as cation.
A cation has smaller size than the neutral atom as the less electrons are attracted towards nucleus and thus feel more effective nuclear charge.
The answers are 1. The ionization energy tends to decrease from the top to the bottom of a group because D. Electrons get farther from the nucleus. 3. When electrons are removed from the outermost shell of a calcium atom, the atom becomes D. a cation that has a smaller radius than the atom.
The correct answer for question 1 is D. Electrons get farther from the nucleus best explains why ionization energy tends to decrease from the top to the bottom of a group
Ionization energy is the energy required to remove an electron from an atom in the gaseous state. As one moves down a group in the periodic table, the ionization energy tends to decrease. This is because each element down the group has an additional shell of electrons. The outermost electrons are farther from the nucleus, which means they experience a weaker effective nuclear charge. The increased distance from the nucleus and the screening effect of the inner electrons make it easier to remove an outer electron, thus decreasing the ionization energy.
The incorrect options can be explained as follows:
A. The number of orbitals increases, not decreases, as one moves down a group, which actually contributes to the decrease in ionization energy.
B. The number of neutrons generally increases as one moves down a group, but this does not directly affect the ionization energy.
C. Electrons do not get closer to the nucleus; in fact, they get farther away as additional electron shells are added, which is why the ionization energy decreases.
The correct answer for question 3 is D. a cation that has a smaller radius than the atom.
When electrons are removed from an atom, the atom becomes a cation (a positively charged ion). In the case of calcium, which has two electrons in its outermost shell, removing these electrons results in a Ca^2+ ion. Because the outermost electrons are no longer there to shield the nuclear charge, the remaining electrons are more strongly attracted to the nucleus. This causes the ion to have a smaller radius than the neutral atom.
The incorrect options can be explained as follows:
A. An anion is formed when an atom gains electrons, not when electrons are removed.
B. An anion would have a larger radius than the neutral atom because the added electrons increase repulsion and decrease the effective nuclear charge.
C. A cation has a smaller radius than the neutral atom, not a larger one, because the loss of electrons increases the effective nuclear charge, pulling the remaining electrons closer to the nucleus."
A dilute, aqueous potassium nitrate solution is best classified as a
(1) homogeneous compound
(2) homogeneous mixture
(3) heterogeneous compound
(4) heterogeneous mixture
A dilute, aqueous potassium nitrate solution is classified as a homogeneous mixture, as it is a uniform mixture of solute and solvent at the molecular level.
Explanation:A dilute, aqueous potassium nitrate solution is best classified as a (2) homogeneous mixture, also known as a solution. This classification is due to the fact that potassium nitrate is a highly soluble ionic compound that, when dissolved in water, dissociates into ions, creating a mixture with a composition that is uniform throughout. Therefore, it is not possible to distinguish between the different components of the mixture, even with a powerful microscope. If we were talking about potassium hydroxide, it would similarly be fully soluble and dissociate completely, yielding a specified concentration of hydroxide ions in the case given. Nevertheless, for potassium nitrate, the dissolution would result in potassium and nitrate ions evenly distributed in the solution.
What kind of bond does these have?
1.tap water
2.distilled water
3.sugar
4.salt
5.salt in distilled water
6.sugar in distilled water
What physical force can cause a change in the state of matter?
Which metal is most likely to form more than one kind of positively charged ion? sodium (Na) barium (Ba) nickel (Ni) magnesium (Mg)
the correct answe is C - nickel (Ni)
Atoms of which element contain 25 protons?
Atoms of manganese contains 25 protons.
An element is the simplest chemical substances that cannot be decomposed in a chemical reaction or by any chemical means and made up of atoms all having the same number of protons.
The identity of an element can be traced to the number of protons in its atom. The number of protons possessed by an atom is the same as its atomic number.
Manganese is a metallic chemical element with symbol Mn and an atomic number of 25.
2. In a molecule represented by the chemical formula C6H12O6, how many atoms of each element are present?
C6H12O6 is sugar.
There are:
6 C (carbon atoms),
12 of H (hydrogen atoms),
6 of O (oxygen atoms).
What mass of CCl4 is formed by the reaction of 5.14 g of methane with an excess of chlorine?
[tex]\boxed{{\text{49}}{\text{.224 g}}}[/tex] of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is produced by the reaction of 5.14 g of methane with an excess of chlorine.
Further explanation:
Stoichiometry of a reaction is used to determine the amount of species present in the reaction by the relationship between the reactants and products. It can be used to determine the moles of a chemical species when the moles of other chemical species present in the reaction is given.
Consider the general reaction,
[tex]{\text{A}} + 2{\text{B}}\to3{\text{C}}[/tex]
Here,
A and B are reactants.
C is the product.
One mole of A reacts with two moles of B to produce three moles of C. The stoichiometric ratio between A and B is 1:2, the stoichiometric ratio between A and C is 1:3 and the stoichiometric ratio between B and C is 2:3.
Limiting reagent:
A limiting reagent is the one that is completely consumed in a chemical reaction. The amount of product formed in any chemical reaction has to be in accordance with the limiting reagent of the reaction. The amount of product depends on the amount of limiting reagent since the product formation is not possible in the absence of it.
The given reaction occurs as follows:
[tex]{\text{C}}{{\text{H}}_4}\left(g\right) + 4{\text{C}}{{\text{l}}_2}\left(g\right)\to{\text{CC}}{{\text{l}}_4}\left(g\right)+4{\text{HCl}}\left(g\right)[/tex]
It is given that chlorine is present in an excess amount so methane [tex]\left({{\text{C}}{{\text{H}}_4}}\right)[/tex] is a limiting reagent and therefore it controls the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] produced during the reaction.
The formula to calculate the amount of [tex]{\text{C}}{{\text{H}}_4}[/tex] is as follows:
[tex]{\text{Amount of C}}{{\text{H}}_4} = \frac{{{\text{Given mass of C}}{{\text{H}}_{\text{4}}}}}{{{\text{Molar mass of C}}{{\text{H}}_{\text{4}}}}}[/tex] …… (1)
The given mass of [tex]{\text{C}}{{\text{H}}_4}[/tex] is 5.14 g.
The molar mass of [tex]{\text{C}}{{\text{H}}_4}[/tex] is 16.04 g/mol.
Substitute these values in equation (1).
[tex]\begin{aligned}{\text{Amount of C}}{{\text{H}}_4} &= \left({{\text{5}}{\text{.14 g}}}\right)\left({\frac{{{\text{1 mol}}}}{{{\text{16}}{\text{.04 g}}}}}\right)\\ &= 0.32044\\&\approx{\mathbf{0}}{\mathbf{.320 mol}}\\\end{aligned}[/tex]
From the balanced chemical reaction, it is clear that 1 mole of [tex]{\text{C}}{{\text{H}}_4}[/tex] produces 1 mole of [tex]{\text{CC}}{{\text{l}}_4}[/tex] .
So the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is equal to that of [tex]{\text{C}}{{\text{H}}_4}[/tex] and thus the amount of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 0.320 mol.
The formula to calculate the mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is as follows:
[tex]{\text{Mass of CC}}{{\text{l}}_4} = \left( {{\text{Moles of CC}}{{\text{l}}_4}}\right)\left({{\text{Molar mass of CC}}{{\text{l}}_4}}\right)[/tex]
…… (2)
The number of moles of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 0.320 mol.
The molar mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] is 153.82 g/mol.
Substitute these values in equation (2).
[tex]\begin{gathered}{\text{Mass of CC}}{{\text{l}}_4} = \left({{\text{0}}{\text{.320 mol}}}\right)\left({\frac{{{\text{153}}{\text{.82 g}}}}{{{\text{1 mol}}}}}\right)\\ = {\mathbf{49}}{\mathbf{.224 g}}\\\end{gathered}[/tex]
Therefore, the mass of [tex]{\text{CC}}{{\text{l}}_4}[/tex] produced is 49.224 g.
Learn more:
1. Calculate the moles of chlorine in 8 moles of carbon tetrachloride: https://brainly.com/question/3064603
2. How many grams of potassium were in the fertilizer? https://brainly.com/question/5105904
Answer details:
Grade: Senior School
Subject: Chemistry
Chapter: Mole concept
Keywords: stoichiometry, reactant, product, limiting reagent, CCl4, CH4, Cl2, molar mass, given mass, amount of CH4, amount of CCl4, 49.224 g, mass of CCl4, 4Cl2, 4 HCl, 5.14 g, 16.04 g/mol.
How many atoms are in 2.70 moles of iron (Fe) atoms?
4.48 × 10-24 atoms Fe
1.63 × 1024 atoms Fe
2.23 × 1023 atoms Fe
6.02 × 1023 atoms Fe
Avogadro's number is the number of units (atoms, molecules) in 1 mole of substance:
6.023 × 10²³ atoms per 1 mole