kai yiu asked in 科學及數學化學 · 1 decade ago

F.4 Chem MC Need Reason!!!

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


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

2 Answers

  • 1 decade ago
    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
  • 1 decade ago

    The molar mass of argon is = 40 g/mol

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