Question

The density of a gas is `1.964 g 1 dm^(-3) at 273 K` and `76 cm Hg`. The gas is
A. `CH_(4)`
B. `CO_(2)`
C. `Xe`
D. `C_(2)H_(6)`

Answer 1

Correct Answer - B
We can identify the gas through its molar mass `(M)`.
According to the ideal gas law, we have
`pM = dRT`
or `M = (dRT)/(p)`
` = ((1.964 g dm^(-3)) (0.0821 dm^(3) "atm" K^(-1) "mol"^(-1)) (273 K))/(((76 cm)/(76 cm "atm"^(-1))))`
`= 44 g mol^(-1)`
Thus , the gas is `CO_(2)` whose molecular mass is `44 a"mu"`.