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Given below are two statements. Statement I: The average momentum of a molecule in a sample of an ideal gas depends on temperature. Statement II: The rms speed of oxygen molecules in a gas is v. If the temperature is doubled and the oxygen molecules dissociate into oxygen atoms, the rms speed will become 2v. In the light of the above statements, choose the correct answer from the options given below.

Asked in JEE Main 28th July 1st Shift 2022 · Dissociation and rms speed

• (1) Both Statement I and Statement II are true.
• (2) Both Statement I and Statement II are false.
• (3) Statement I is true but Statement II is false.
• (4) Statement I is false but Statement II is true.

Step-by-step solution

Why the other options are wrong

• (1) Accepts Statement I, but the average momentum vector is zero at every temperature; it is the average speed that grows.
• (2) Rejects Statement II, but the mass halving and the temperature doubling together give exactly a factor 2.
• (3) Reverses both judgements.

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