Question 1

1 L closed flask contains a mixture of 4 g of methane and 4.4 g of carbon dioxide. The pressure inside the flask at 27^ C is [Assume ideal behaviour of gases]

Accepted Answer

no. of moles of CH _4 ( n _1 )= 4 16 =0.25 ~mol no. of moles of CO _2 ( n _2 )= 4.4 44 =0.1 ~mol Total no. of moles ( n _ T )= n _1+ n _2=0.35 ~mol P= 0.35 0.082 300 1 =8.6 ~atm

Question 2

In which mode of expression, the concentration of a solution remains independent of temperature?

Accepted Answer

Molality-Moles of solute/mass of solvent in kg Molality does not involve volume term. It is independent of temperature.

Question 3

A certain metal sulphide, M S_2, is used extensively as a high temperature lubricant. If MS _2 is 40.06 \% by mass sulphur, metal M has atomic mass.

Accepted Answer

M S_2=M+32 2=M+64 \% of sulphur = ( 64 M+64 ) 100=40.06 M+64= 6400 40.06 M+64=160 M=160-64=96 u

Question 4

If 0.2 gram of an organic compound containing carbon, hydrogen and oxygen on combustion, yielded 0.147 gram carbon dioxide and 0.12 gram water. What will be the content of oxygen in the substance?

Accepted Answer

\% of C = 12 44 0.147 0.2 100=20.045 \% \% of H = 2 18 0.12 0.2 100=6.666 \% \% of O =100-(20.045+6.666)=73.29 \%

Question 5

An ideal gaseous mixture of ethane ( C _ 2 H _ 6 ) and ethene ( C _ 2 H _ 4 ) occupies 28 litre at 1 atm and 273 ~K . The mixture reacts completely with 128 ~g O _ 2 to produce CO _ 2 and H _ 2 O . Mo

Accepted Answer

C _ 2 H _ 6 +3.5 O _ 2 2 CO _ 2 +3 H _ 2 O ; C _ 2 H _ 4 +3 O _ 2 2 CO _ 2 +2 H _ 2 O Let volume of ethane is x litre, 22.4 4=3.5 x +3(28- x ) x =11.2 litre at constant T and P , V n ; Mole fraction of C _ 2 H _ 6 in mixture = 11.2 28 =0.4

Question 6

The amount of H _ 2 O _ 2 present in 1 litre of 1.5 ~N H _ 2 O _ 2 solution, is:

Accepted Answer

Molecular weight of H _ 2 O _ 2 =34 Equivalent weight of H _ 2 O _ 2 =17 1 ~L of 1 ~N H _ 2 O _ 2 has =17 ~g of H _ 2 O 1 Lof 1.5 NH _ 2 O _ 2 has =1.5 17=25.5 ~g of H _ 2 O _ 2

Some Basic Concepts of Chemistry — Previous Year Questions & Solutions