Solutions Test -15

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Solutions Test -15

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Weekly Quiz Competition

Question 1
1 / -0

The statement the mass of a gas dissolved in a given mass of a solvent at any temperature is proportional to the pressure of the gas above the solvent is :

A
Dalton's Law of Partial Pressures

B
Law of Mass Action

C
Henry's Law

D
None of these

Solution

Henry’s Law states that the mass of a gas dissolved in a given mass of a solvent at any temperature is proportional to the pressure of the gas above the solvent.
Question 2
1 / -0

25ml of 3.0M HNO₃ is mixed with 75ml of 4.0M HNO₃. If the volumes are additive, the morality of the final mixture would be :

A
3.25 M

B
4.0 M

C
3.75 M

D
3.50 M

Solution

M₁V₁+ M₂V₂= MV
Question 3
1 / -0

10 liter solution of urea contains 240 g urea. The active mass of urea will be

A
0.04

B
0.02

C
0.4

D
0.2

Solution

∵ 10 liter of urea solution contains 240 gm of urea

Active mass = 240/60×10

= 0.4
Question 4
1 / -0

The sum of the mole fraction of the components of a solution is

A
0

B
1

C
2

D
4

Solution

Sum of mole fraction is always 1.

Question 5

1 / -0

Vapour pressure of a solvent containing nonvolatile solute is_________.

more than the vapour pressure of a solvent

less than the vapour pressure of solvent

equal to the vapour pressure of solvent

none

Solution

At any given temperature, the vapor pressure of a solution containing a nonvolatile solute is less than that of the pure solvent. This effect is called vapor pressure lowering. The solid line in Figure is a plot of the vapor pressure of pure water versus temperature. The break in the curve at 0°C is the intersection of the curve of the vapor pressure of the solid with the curve of the vapor pressure of the liquid. The dashed line in is a plot of the vapor pressure of an aqueous solution of sugar versus temperature. Notice that the vapor pressure of the solution is always less than that of the pure solvent.

The vapor pressure of pure water is shown as a solid line; the vapor pressure of an aqueous solution is shown as a dashed line. Note the differences between the solution and the pure substance in melting point and boiling point.

The surface of a pure solvent is populated only by solvent molecules. Some of these molecules are escaping from the surface, and others are returning to the liquid state. The surface of a solution is populated by two kinds of molecules; some are solvent molecules,

Question 6
1 / -0

The vapour pressure of a dilute solution of a solute is not influenced by:

A
temperature of solution

B
melting point of solute

C
mole fraction of solute

D
degree of dissociation of solute

Solution

Vapour pressure of a dilute solution depends upon the temperature, mole fraction, and degree of dissociation of solute and independent of the melting point of solute.
Hence, option (B) is correct.
Question 7
1 / -0

Which of the following conditions is not correct for ideal solution

A
no change in volume on mixing

B
no change in enthalpy on mixing

C
it obeys Raoults law

D
lonisation of solute should occurs to a small extent

Solution

In an ideal solution, no change in volume on mixing, no change in enthalpy on mixing and it obeys Raoults law but ionisation of solute should not occur to a small extent.
So answer D.
Question 8
1 / -0

The relative lowering in vapour pressure is proportional to

A
$$ X_{solute}$$

B
$$\frac {1}{X_{solute}}$$

C
$$\,\,\, m$$

D
None of the above

Solution

The vapor pressure of a liquid is the pressure of a vapor in equilibrium with the liquid phase. The vapor pressure lowering relative to pure solvent is proportional to the mole fraction of solute.
Relative lowering vapor pressure $$\alpha \ X_{solute}$$
Question 9
1 / -0

The boiling point of $$C_6H_6, CH_3OH, C_6H_5NH_2\,\, and \,\,C_6H_5NO_2 \,\,are\,\, 80^o C, 65^o C, 184^o C \,\,and \,\,212^o C$$ respectively. Which will show highest vapour pressure at room temperature:

A
$$C_6H_6$$

B
$$CH_3OH$$

C
$$C_6H_5NH_2$$

D
$$C_6H_5NO_2$$

Solution

Vapour pressure : At a constant temperature, the pressure exerted by the vapours of a liquid on its surface when they (liquid and its vapours) are in equilibrium, is know as vapour pressure.
So compound with lower boiling point have higher vapour pressure.
Question 10
1 / -0

In which of the following, the van't Hoff factor (i) is equal to one?

A
$$NaCl$$

B
$$KNO_3$$

C
$$Urea$$

D
All of these

Solution

Van't Hoff factor (i) is equal to no of ions in solution.

$$NaCl \to Na^+ + CL^- $$ $$i = 2$$ ions

Since urea is a non-electrolyte, Hence, the Van't Hoff factor is equal to $$1$$.

$$KNO_3 \to K^+ + {NO_3}^{-} $$ $$i = 2$$ ions.
Question 11
1 / -0

Which compound corresponds van't Hoff factor (i) to be equal to 2 in dilute solution:

A
$$K_2SO_4$$

B
$$NaHSO_4$$

C
Sugar

D
$$MgSO_4$$

Solution

vant Hoff factor (i) is equal to no of ions in solution.
$$MgSO_4$$ = 2 ions
$$NaHSO_4$$ = 3 ions
Sugar = 1 molecule
$$K_2SO_4$$ = 3 ions
Question 12
1 / -0

The Van't Hoff factor ($$i$$) for $${Na}_{2}S{O}_{4}$$ is:

A
3

B
2

C
1

D
0

Solution

$$Na_2SO_4$$ is a strong electrolyte. It dissociates into $$Na_2SO_4 \rightarrow 2Na^+ + SO_4^{2-}$$

Hence, $$ i=3.$$

So, option A is correct
Question 13
1 / -0

If in solvent, n simple molecules of solute combine to form an associated molecule, $$x$$ is degree of association the Van't Hoff's factor $$'i'$$ is equal to:

A
$$\;\displaystyle\frac{1}{1-nx}$$

B
$$\;\displaystyle\frac{1-x+nx}{1}$$

C
$$\;\displaystyle\frac{1-x+\displaystyle\frac{x}{n}}{1}$$

D
$$\;\displaystyle\frac{\displaystyle\frac{x}{n}-1+x}{1}$$

Solution

In solvent, n simple molecules of solute combine to form an associated molecule, $$x$$ is degree of association the Van't Hoff's factor $$'i'$$ is equal to:
$$Van't\quad Hoff's\quad factor(i)=\quad \dfrac { 1-x+\dfrac { x }{ n } }{ 1 }$$
$$x$$=degree of association,
$$n$$=simple molecule of solute combine to form an associated molecule,
$$i$$= Van'tHoff's factor.
So the answer is C.
Question 14
1 / -0

The Van't Hoff factors $$i$$ for an electrolyte which undergoes dissociation and association in solvents are respectively:

A
greater than one and less than one

B
less than one and greater than one

C
less than one and less than one

D
greater than one and greater than one

Solution

In case of association of solute particles in solution, the observed molecular weight of solute being more than the normal, the value of factor 'i' is less than unity (i.e. i < 1), while for dissociation the value of i is greater than unity (i.e. i > 1), because the observed molecular weight has lesser value than normal molecular weight.

Hence, the correct option is $$A$$

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Solutions Test -15

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Solutions Test -15

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SHARING IS CARING

Question 1

Dalton's Law of Partial Pressures

Law of Mass Action

Henry's Law

None of these

Solution

Question 2

3.25 M

4.0 M

3.75 M

3.50 M

Solution

Question 3

0.04

0.02

0.4

0.2

Solution

Question 4

0

1

2

4

Solution

Question 5

more than the vapour pressure of a solvent

less than the vapour pressure of solvent

equal to the vapour pressure of solvent

none

Solution

Question 6

temperature of solution

melting point of solute

mole fraction of solute

degree of dissociation of solute

Solution

Question 7

no change in volume on mixing

no change in enthalpy on mixing

it obeys Raoults law

lonisation of solute should occurs to a small extent

Solution

Question 8

$$ X_{solute}$$

$$\frac {1}{X_{solute}}$$

$$\,\,\, m$$

None of the above

Solution

Question 9

$$C_6H_6$$

$$CH_3OH$$

$$C_6H_5NH_2$$

$$C_6H_5NO_2$$

Solution

Question 10

$$NaCl$$

$$KNO_3$$

$$Urea$$

All of these

Solution

Question 11

$$K_2SO_4$$

$$NaHSO_4$$

Sugar

$$MgSO_4$$

Solution

Question 12

3

2

1

0

Solution