UPSEE Solved Model Paper 7

given:
Volume of Cl2 gas V = 1 L
Temperature, T = 10°C
= 10 +273 (1°C = 273 K)
= 283 K
Pressure, P = 750 mm =

750

760

atm
Applying ideal gas equation, i.e
PV = nRT (i)
where n = Number of moles
R = Gas constant = 0.082 L atm K−1‌mol
From equation (i), we get
n =

PV

RT

Substituting all the values, we get
n =

750

760×0.082×283

= 0.0425
or,
Number of moles of CI2 = 0.0425
Reaction between potassium iodide and CI2 is:
2KI + Cl2 → 2KCl + I2
Now, from above reaction,
Moles of CI2 = Moles of I2 liberated
Thus, used moles of I2 = 0.0425
Molecular mass of I2 = 2 × 126.90
= 253.8 gmol−1
Now, number of moles is given by:
Number of moles =

Moles‌of‌I2

Molecular‌mass‌of‌I2

Substituting the values in above equation, we get
0.0425 =

Mass‌of‌I2

253.8

Mass of I2 liberated = 0.0425 × 253.8
= 10.7865 g
~ 10.78 g
Hence, option 'A' is correct.