UPSEE Solved Model Paper 7

Given:
Volume of gas = 1L
Mass of gas = 2 g
Temperature = 300 K
Pressure = 1 atm
IdeaI gas equation is:
p V = n R T ... (i)
w here, p = Pressure
V = Volume
n = No. of moles
R = Gas constant = 0.082 L atm K−1mol−1
T = Temperature
Let molar m ass of the gas be 'M' g/mol.
As we know, no of moles, n is given as
n =

Molar

Molar‌mass

... (ii)
Substituting values in equation (ii), we get
n =

2

M

Substituting values in equation (i), w e get
1 × 1 =

2

M

× 0.082 × 300
M = 2 × 0.082 × 300
= 48.2 g/mol
Now if:
p = 0 75 atm
V = 1L
mass = 1 g
Molar mass = 49.2 g/mol
Let the temperature be 'T' K
Substituting values in equation (ii). w e getNo. of moles, n' =

1

49.2

Substituting values in equation (t), we get
0.75 × 1 =

1

49.2

×0.082×T
T =

0.75×49.2

0.082

= 450 K
Hence, option； 'A' is correct.