Question

5g of each of the following gases at 87°c and 750 mm pressure are taken. which of them will have the least volume?

Answer 1

At given temperature and pressure , volume of a gas depends upon its  number of moles.

volume of gas=number of moles the gas = mass of the gas/ molecular mass of the gas.

because mass of all the gas is same.

Thus 

the gas with minimum molecular mass will have the maximum volume.

Here HF has the minimum molecular mass thus its volume will be maximum.

Answer 2

HI have the least volume.

Step-by-step explanation:

Given:

Here, 5g of each of the following gases at 87°c and 750 mm pressure are taken.

Now, from Ideal gas law,

$PV = \dfrac{Weight}{Molar\ mass}\times RT$

The gas with maximum molecular weight will have minimum volume.  

So, HI has the maximum molecular weight, hence it has the least volume.