Your instructor is probably expecting the answer B) III only.
III) The evolution or <em>absorption of heat</em> is evidence of a <em>chemical change</em>.
I) Boiling water and IV) mixing paint are <em>physical changes</em>.
II) A change in colour on mixing is usually an indication of a reaction (but not when mixing paint). However, in this case, the lighter blue colour might have happened simply because you are diluting the solution. You would have to do an experiment which is correct.
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Answer:</h3>
Chlorine gas (Cl₂)
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Explanation:</h3>
- According to the Graham's law of diffusion, the diffusion rate of a gas is inversely proportional to the square root of its density or molar mass.
- Therefore, a lighter gas will diffuse faster at a given temperature compared to a heavy gas.
- Consequently, the heavier a gas is then the denser it is and the slower it diffuses at a given temperature and vice versa.
In this case we are given gases, CI₂
, H₂,He and Ne.
- We are required to identify the gas that will diffuse at the slowest rate.
- In other words we are required to determine the heaviest gas.
Looking at the molar mass of the gases given;
Cl₂- 70.91 g/mol
H₂- 2.02 g/mol
He - 4.00 g/mol
Ne- 20.18 g/mol
Therefore, chlorine gas is the heaviest and thus will diffuse at the slowest rate among the choices given.
<span>The combined gas equation relates three variables pressure, temperature and volume when the number of moles is constant.
The equation is PV / T = constant. Which is valid for a fixed number of moles of the gas.
You can derive the combined gas equation from the combination of Bolye's law, Charles' law and Gay-Lussac's law, which needs some algebra.
Answer: option 2. number of moles.
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