F.4 Chem MC Need Reason!!!

Question

Which of the following gases, each having a mass of 3.0 g, has the

largest no. of molecules at room temperature and pressure?

(Relative atomic masses: H= 1.0, C= 12.0, N= 14.0, O= 16.0, F= 19.0, Ar= 40.0)

A. Oxygen

B. Hydrogen fluoride

C. Carbon dioxide

D. Argon

Update:

Why the molar mass of Argon is 36? not 40?

Answer 1

Favorite Answer

First of all, comparing their molar mass:

Oxygen = 32 g/mol

Hydrogen fluoride = 20 g/mol

Carbon dioxide = 44 g/mol

Argon = 36 g/mol

Then for the same mass of each of them, the one with smallest molar mass will contain the largest no. of moles, i.e. hydrogen fluoride.

Ans = B

2009-08-02 12:13:21 補充：

Yes, Argon molar mass = 40

But this will not affect the ans of this Q

2009-08-03 12:13:32 補充：

Yes, but the ans is not affected, still B

Source(s): Myself

Answer 2

The molar mass of argon is = 40 g/mol