The mass of 800cm³ of a gas X at s.t.p. is 1.0g. What is the molar mass of X? [1 mole of a gas at s.t.p occupies 22.4dm³]

A. 18.0g mol‾¹
B. 22.4g mol‾¹
C. 28.0gmol‾¹
D. 36.0gmol‾¹

Correct Answer: Option C

C. 28.0gmol‾¹

Explanation

The mass of 0.8dm³ of a gas at s.t.p. is 1.0g

:. 22.4dm³ of gas at s.t.p. will have a molar mass of 22.4/0.8 = 28.0g mol‾¹