Question

if the mole ratio between a and b is 0.2 then the mole fraction is

Answer 1

Answer:

13.88

Explanation:

Given that

x  

B

​

=0.2,x  

A

​

=0.8

Now,

Molality (m)=  

x  

A

​

×M  

A

​

 

x  

B

​

×1000

​

=  

0.8×18

0.2×1000

​

=13.88m

where,

M  

A

​

= molar mass of solvent

Answer 2

Explanation:

Correct option is

D

0.2

P

B

o

P

A

o

=

2

1

Let, P

A

o

=1

P

B

0

=2

Similarly, n

A

=1andn

B

=2

By Raoult's law,

P

A

=X

A

P

A

o

∴P

A

=

3

1

×1=

3

1

&P

B

=X

B

P

B

o

=

3

2

×2=

3

4

P

A

=X

A

×P

T

∴

3

1

=X

A

×(

3

1

+

3

4

)

∴X

A

=

5/3

1/3

=

5

1

=0.2

Hence, option D is correct.