An example of a physical change is grinding pepper. Physical change is when there is no change in the chemical composition of the substance.
What are physical changes?Physical changes are those changes in which the physical composition of the substance changes but the chemical composition of the substance or compound remains the same.
Examples are ice melting into water. It is a physical change. Like here, the baking cake is a chemical change in which the substance changes into other substances.
And grill lighting is a chemical change. Toasting bread is a chemical change in which the bread substance is burning. Pepper grinding is a process of physical change because it's just crushing the pepper.
Therefore, an example of physical change is grinding pepper.
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How do the independent and dependent variables in an experiment compare?
Answer:
The independent variable controls the dependent variable.
Explanation:
Radioactive isotopes of an atom are?
Radioactive isotope, also called radioisotope, radionuclide, or radioactive nuclide, any of several species of the same chemical element with different masses whose nuclei are unstable and dissipate excess energy by spontaneously emitting radiation in the form of alpha, beta, and gamma rays.
Answer:
Less stable
Explanation:
I took the K12 test
How many grams of magnesium oxide can be produced when 97.2 g Mg react with 88.5 g O2?
Unbalanced equation: Mg + O2 → MgO
What is the smallest part of Substance called?
A. Element
B. Atom
C. Mixture
D. Molecule
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Write a brief explanation about why a plant extract is a mixture
A plant extract is a mixture due to the fact that it contains multiple compounds physically combined, they retain their individual characteristics. This makes the composition of extracts heterogeneous. Mixtures in the form of plant extracts are especially important in pharmaceutical science.
Explanation:A plant extract is considered a mixture due to the fact that it contains multiple compounds physically combined, not chemically bonded. These compounds usually include various elements of the plant like oils, pigments, and other organic molecules, all present in varying amounts. The plant extract retains the characteristics of its individual components because they are not chemically reacting with one another, but simply mixed together, making it a heterogeneous mixture, as the same drop of the extract might have different compounds in different proportions.
This is not much unlike the example of an Italian dressing, where in different parts of the mixture you may find more oil or vinegar or herbs because the ingredients separate and settle unevenly throughout the mixture. Similarly, in a plant extract, the compounds will not be proportionately arranged in every drop of the mixture.
Particularly in pharmaceutical science, this heterogeneous nature is an advantage as different plants contain unique combinations of beneficial compounds. Examples include medicines such as aspirin and codeine, which were once derived from plant extracts. This demonstrates the importance of mixtures in medicinal applications.
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what is the volume, in liters, of 2.00 moles of hydrogen H at STP
Final answer:
To find the volume of 2.00 moles of hydrogen gas at STP, multiply the number of moles by the standard molar volume, 22.4 L/mol, resulting in 44.8 liters.
Explanation:
The volume of hydrogen gas at STP (Standard Temperature and Pressure) can be found using the standard molar volume. By definition, the standard molar volume of an ideal gas at STP, which is 0°C (273 K) and 1 atm pressure, is 22.4 liters per mole.
For 2.00 moles of hydrogen gas at STP, the calculation simply involves multiplying the number of moles by the standard molar volume:
Volume = 2.00 moles × 22.4 L/molVolume = 44.8 litersThus, 2.00 moles of hydrogen gas at STP occupy a volume of 44.8 liters.
Which type of substance is graphene?
A-atom
B- molecule
C-compound
Will mark brainliest
Answer: B- molecule
Explanation:
An atom is the smallest entity of a substance which may or may not have independent existence.
Molecule is a pure substance which is composed of similar kind of atoms.It can not be decomposed into simpler constituents using chemical reactions.Example: Hydrogen [tex]H_2[/tex]
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.It can be decomposed into simpler constituents using chemical reactions. Example: water [tex]H_2O[/tex]
Graphene is a crystalline allotrope of carbon and thus is a molecule as it is made up of similar kind of atoms.
A newly discovered element, Y, has two naturally occurring isotopes. 87.8 percent of the sample is an isotope with a mass of 267.8 u, and 12.2 percent of the sample is an isotope with a mass of 269.9 u. What is the weighted average atomic mass for this element? 267.9 u 268.1 u 268.9 u 269.1 u
Answer : The average atomic mass of this element is, 268.1 u
Explanation :
Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.
Formula used to calculate average atomic mass follows:
[tex]\text{Average atomic mass }=\sum_{i=1}^n\text{(Atomic mass of an isotopes)}_i\times \text{(Fractional abundance})_i[/tex]
For isotope-1 :
Mass of isotope-1 = 267.8 amu
Fractional abundance of isotope-1 = 87.8 % = 0.878
For isotope-2 :
Mass of isotope-2 = 269.9 amu
Fractional abundance of isotope-2 = 12.2 % = 0.122
Putting values in equation 1, we get:
[tex]\text{Average atomic mass }=[(267.8\times 0.878)+(269.9\times 0.122)][/tex]
[tex]\text{Average atomic mass }=268.1u[/tex]
Thus, the average atomic mass of this element is, 268.1 u
If a system has 425 kcal of work done to it, and releases 5.00 × 102 kJ of heat into its surroundings, what is the change in internal energy of the system?
Using the first law of thermodynamics, the change in internal energy of the system, given the work done on the system and the heat released by the system, was calculated to be -2.28 × 10^6 Joules.
Explanation:The subject of this problem is a classic concept in thermodynamics: the conservation of energy. According to the first law of thermodynamics, the change in the internal energy (ΔU) of a system is the sum of the heat (Q) added to the system and the work (W) done on the system, expressed in the equation ΔU = Q - W.
In this case, the work is performed on the system, amounting to 425 kcal. To convert this into a common unit like Joules, use the conversion factor 1 kcal = 4.184 × 10^3 J. Therefore, the work done on the system (W) is 425 kcal × (4.184 × 10^3 J/kcal) = 1.78 × 10^6 J.
The heat released by the system (Q) is - 5.00 × 10^2 kJ (the negative sign indicates heat is lost from the system). Converting into Joules gives -5.00 × 10^2 kJ × (10^3 J/kJ) = -5.00 × 10^5 J.
Substituting Q and W into the equation gives ΔU = (-5.00 × 10^5 J) - (1.78 × 10^6 J) = -2.28 × 10^6 J. Hence, the change in internal energy of the system is -2.28 × 10^6 J.
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The change in internal energy of the system is -1277.4 kJ.
Explanation:The change in internal energy of a system can be calculated using the equation:
Change in internal energy = heat transfer - work done
In the given scenario, the system receives 425 kcal of work and releases 5.00 × 102 kJ of heat. To calculate the change in internal energy, we need to convert the units to a consistent format. 1 kcal = 4.184 kJ, so the work done is 425 kcal x 4.184 kJ/kcal = 1777.4 kJ.
Using the formula, the change in internal energy is:
Change in internal energy = 5.00 × 102 kJ - 3 kJ = -1277.4 kJ
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Which of these is a physical property?
Question options:
malleable
easy to digest
does not burn
becomes moldy quickly
Which of the following is designed to convert energy into mechanical energy?
A.Blender
B.Kerosene heater
C.Flashlight
D.Baking oven
How do I identify the ions present in K2HPO4?
Final answer:
In K2HPO4, the ions present are potassium ions (K+) and hydrogen phosphate ions (HPO42-). Hydrogen phosphate can further dissociate, but the dissociation leading to the formation of PO43- is much less due to the small value of the equilibrium constant. Hence, the solution is basic.
Explanation:
To identify the ions present in K2HPO4, we first consider the fact that K2HPO4 is a salt derived from the reaction of a strong base (KOH) with a weak acid (H3PO4), and it is made up of potassium ions (K+) and hydrogen phosphate ions (HPO42-). In aqueous solution, K2HPO4 fully dissociates into these ions:
K2HPO4 (s) → 2 K+ (aq) + HPO42- (aq)
The potassium ions, K+, are the cationic species and the HPO42- ions are the anionic species. The hydrogen phosphate ion is an amphiprotic species, meaning it can act as both an acid and a base. This ion may further dissociate in water:
First ionization: H2PO4- (aq) → H+ (aq) + HPO42- (aq)
Second ionization: HPO42- (aq) + H2O(l) ⇌ H3O+ (aq) + PO43- (aq)
However, the second ionization, which forms PO43- and H3O+, has an equilibrium constant (K2), which is much less than that of the first ionization, indicating that it occurs to a significantly lesser extent. The solution of K2HPO4 is basic because the K2 of the HPO42- ion is much larger than the acidic dissociation constant.
Can an element with eight valence electrons still be reactive?
how small do you think an individual atom is
how many atoms of oxygen are contained in 47.6g of Al2(CO3)3? The molar mass of Al2(CO3)3 is 233.99g/mol.
Which is the most accurate description of compounds?
a. They are formed by elements that join in any given mass ratio.
b. They have the same properties as the elements that make them up.
c.They have a unique set of properties that can be used as identifiers.
d. They cannot be broken down into the elements that form them through chemical changes.
Answer: c.They have a unique set of properties that can be used as identifiers.
Explanation:
Compound is a pure substance which is made from atoms of different elements combined together in a fixed ratio by mass.
Compounds can be decomposed into simpler constituents using chemical reactions.
Example: Water [tex](H_2O)[/tex]
[tex]2H_2O\rightarrow 2H_2+O_2[/tex]
Compounds have different properties than the elements it is made up of.
Thus the most accurate description of compounds is that they have a unique set of properties that can be used as identifiers.
Magma is made up of melted or *blank* materials.
A. Intrusive
B. Molten
C. Extrusive
D. Cooled
While visiting the Grand Canyon, you observe the exposed layers of rock in the valley. What natural process most likely caused the valley to form? Deposition Chemical weathering Oxidation Erosion
Answer: it would be erosions
Explanation:
The natural process most likely caused the valley to canyon is tectonic uplift and erosion.
What is tectonic uplift?Tectonic uplift is defined as the portion of the total geologic uplift to the mean of the earth surface that is not attributable to an isostatic response to an unloading.
Tectonic plate is defined as a scientific theory explaining how large landforms are formed as a result of subsurface motions on Earth.
Erosion is defined as the geological process in which earthen materials will move away and transported by the natural force such as wind and water.
There are basically two types of erosion
Surface erosionMass movement erosionThus, the natural process most likely caused the valley to canyon is tectonic uplift and erosion.
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At room temperature, which of these are oxide minerals? Select all that apply.
A.H2OB.CO2C.Al2O3D.Fe3O4
Answer: C.[tex]Al_{2}O_{3}[/tex] and D.[tex]Fe_{3}O_{4}[/tex]
Explanation: Oxide minerals are the minerals in which the oxide anion is bonded to the central metal atom. These are useful for industrial purposes.
Out of the given options, only two of them can be categorized as the oxide minerals.
H2O and CO2 will not be considered as oxide minerals.
Water particles in gas coming off a pan of boiling water are moving faster or slower than the particles of the water in the pan
Answer:
faster.
Explanation:
Particles of water in the gas coming out of a pot of boiling water are moving faster than particles of water in the pot.
This is because the heat energy makes the molecules move faster, so the molecules "trapped" in the liquid are able to gradually break down the barriers of the liquid-air interface and, therefore, the amount of water. it decreases until it "disappears". When you boil water, that smoke you see coming out is nothing more than a bunch of molecules that have broken through the barrier and are free, gaseous. This was due to the rapid movement of these molecules.
We want to see what happens to the particle's speed in a given material as the temperature changes (increases in this case) and it faces a change of phase.
We will see that the particles in the gas (vapor of water) have a larger speed than the ones in the liquid water.
--------------------------------
To see this, first, we need to understand how the temperature manifests in a given material.
As we increase the temperature of the material, the kinetic energy of the particles that make the material increase (thus the speed increases). This causes the particles to move more, and this is why as we increase the temperature, is likely to see an increase in the volume.
This is the reason of why we usually see that a solid has less volume than a liquid, and a liquid has less volume than a gas (for the same mass of the same material).
Then as we increase the temperature of liquid water and that water starts to change of phase (by boiling) the kinetic energy of the particles increase, and thus, the speed increases.
Then the particles will be moving faster than the particles of the water in the pan.
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Does H₂O have a subscript?
Which example provides a complete scientific description of an object in motion? Question 3 options: The marble changed position quickly. The car traveled north. The marble moved 30 cm north in 6 seconds. The ball rolled 20 cm in 5 seconds.
Answer:
The marble moved 30 cm north in 6 seconds. is correct
Explanation:
according to K12
100% sure
Which of the following statements is FALSE? A. Air temperatures over the ocean remain fairly constant throughout a 24-hour cycle. B. Air temperatures over the land can vary significantly throughout the day. C. Air temperatures over land reach their highest values in the mid-afternoon. D. Air temperatures over land are always higher than air temperatures over the ocean.
Answer:
d
Explanation:
Air temperatures over land are always higher than air temperatures over the ocean. This statement is false.
What is temperature ?The physical concept of temperature indicates in numerical form how hot or cold something is. A thermometer is used to determine temperature. Thermometers are calibrated using a variety of temperature scales, which historically defined distinct reference points and thermometric substances.
Above the course of a 24-hour cycle, air temperatures over the ocean remain largely unchanged. Throughout the day, there can be large variations in the air temperature over the land. Mid-afternoon is when land-based air temperatures are at their maximum. Always higher than air over the ocean are air temperatures over land.
Water has a heat capacity that is around four times more than that of land, meaning it requires more energy to heat it up and reacts more slowly to temperature
Thus, option D is correct.
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What was rutherfords contribution to the structure of an atom
The Nuclear Model-1909
Some common substances used in the laboratory are listed in the table. The chemical formulas of the substances are also listed beside their names.
How many of the listed items are elements?
Answer:5
Explanation:
5
Copper, sulfur, gold, iron, and aluminum are elements, as their symbols suggest. The other four substances are compound with two elements each.
balance the following reaction. CH4+O2==>CO2+H20
Answer:
[tex]\huge \boxed{\mathrm{CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O}}[/tex]
[tex]\rule[225]{225}{2}[/tex]
Explanation:
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 + H_2O[/tex]
Balancing the Hydrogen atoms on the right side,
[tex]\sf CH_4+ O_2 \Rightarrow CO_2 +2 H_2O[/tex]
Balancing the Oxygen atoms on the left side,
[tex]\sf CH_4+ 2O_2 \Rightarrow CO_2 +2 H_2O[/tex]
[tex]\rule[225]{225}{2}[/tex]
How many molecules are in each sample?4.6 g H2O
Answer: The number of molecules present in given amount of water are [tex]1.54\times 10^{23}[/tex]
Explanation:
To calculate the number of moles, we use the equation:
[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]
Given mass of water = 4.6 g
Molar mass of water = 18.0 g/mol
Putting values in above equation, we get:
[tex]\text{Moles of water}=\frac{4.6g}{18.0g/mol}=0.255mol[/tex]
According to mole concept:
1 mole of a compound contains [tex]6.022\time 10^{23}[/tex] number of molecules.
So, 0.255 moles of water will contain [tex]0.255\times 6.022\times 10^{23}=1.54\times 10^{23}[/tex] number of molecules.
Hence, the number of molecules present in given amount of water are [tex]1.54\times 10^{23}[/tex]
scientists build theories to test their ideas about things that they cannot observe directly true or false?
Difference between osmosis and diffusion
Osmosis occurs through a semipermeable membrane
Net movement in osmosis is from areas of higher concentration to areas of lower concentration
Osmosis requires facilitation by an energy carrying molecule, such as ATP. Diffusion requires no additional energy to move molecules across the concentration gradient.
Osmosis is used for gases, such as oxygen and carbon dioxide. Diffusion is used for water that contains salt or sugar molecules.
PLEASE NO GUESSING OR INCORRECT ANSWERS.
Herbicides:
1.are used to kill insects
2.can increase crop yields by killing weeds
3.supply plants with nutrients and minerals
4.are only used with hybrid plants
Answer:
The correct answer is number 2: herbicides can increase crop yields by killing weeds.
Explanation:
Herbicides are chemiclas used to avoid the spreding of undesired plants (weeds) on crops. These weeds would be prejudicial to the harvest, therefore, herbicide use can increase crop yields.