Solutions Test 38

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Solutions Test 38

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Weekly Quiz Competition

Question 1
1 / -0

In Dumas' method of estimation of nitrogen 0.35 g of an organic compound gave 55 mL of nitrogen collected at 300 K and 715 mm pressure. The percentage composition of nitrogen in the compound would be:
(Aqueous tension at 300 K = 15 mm)

A
14.45%

B
15.45%

C
16.45%

D
17.45%

Solution
Question 2
1 / -0

A gaseous mixture of $$He$$ and $${{\text{O}}_2}$$ is found to have a density of $${\text{0}}{\text{.543}}\;{\text{d}}{{\text{m}}^{ - 3\;}}{\text{at}}\;{\text{2}}{{\text{7}}^{\text{o}}}{\text{C}}$$ and 760 torr. The percent of mass of helium in the mixture is:

A
66.5

B
33.5

C
19.75

D
80.12
Question 3
1 / -0

When NaCl is dissolved in water

A
boiling point of solution decreases

B
boiling point of solution increases

C
boiling point of solution remains unchanged

D
freezing point of solution increases
Question 4
1 / -0

The amount of anhydrous $$Na_{2}CO_{3}$$ present in 250 ml of 0.25 M solution is

A
6.225 g

B
66.25 g

C
6.0 g

D
6.625 g

Solution
Question 5
1 / -0

Moles of $${\text{N}}{{\text{a}}_{\text{2}}}{\text{S}}{{\text{O}}_{\text{4}}}$$ to be dissolved in 12 moles of water to lower its vapour pressure by 10mm Hg at a temperature at which vapour pressure of pure water is 50 mm Hg is:

A
1.5 moles

B
2 moles

C
1 mole

D
3 moles

Solution
Question 6
1 / -0

Vapour pressure of a pure liquid X is 2 atm at 300 K. It is lowered to 1 atm on dissolving 1 g of Y in 20 g of liquid X. If molar mass of X is 200, what is the molar mass of Y?

A
20

B
10

C
100

D
30

Solution
Question 7
1 / -0

When solute and solvent both are volatile, the vapour pressure of solution is directly proportional to mole fraction of which?

A
Solute

B
Solvent

C
Solute and Solvent

D
none
Question 8
1 / -0

Four solutions of $$K_2SO_4$$ with the following concentration $$0.1 m$$, $$0.01 m$$, $$0.001 m$$ and $$0.0001 m$$ are available. The maximum value of van't Hoff factor, i, corresponds to:

A
0.0001 m solution

B
0.001 m solution

C
0.01 m solution

D
0.1 m solution

Solution
Question 9
1 / -0

The vapour pressure of $$CCl_4$$ at $$25^0C$$ is 143 mm of Hg. 0.5 gm of a non-volatile solute(mol. wt. 65) is dissolved in 100ml of $$CCl_4$$, the vapour pressure of the solution will be:

A
199.34 mm Hg

B
143.99 mm Hg

C
141.43 mm Hg

D
94.39 mm Hg
Question 10
1 / -0

$$0.6g$$ urea is added to $$360g$$ water. Calculate lowering in vapor pressure for this solution
(Given: Vapour pressure of $$H_2O$$ is $$35mm$$ of $$Hg$$)

A
$$0.027mm$$ of $$Hg$$

B
$$0.035mm$$ of $$Hg$$

C
$$0.017mm$$ of $$Hg$$

D
$$0.040mm$$ of $$Hg$$

Solution

Solution:- (C) $$0.017mm$$ of $$Hg$$
$$\dfrac{P^0-Ps}{P^0}=\dfrac{n}{n+N}$$
Lowering in V.P.= $$P^0\times \dfrac{n}{n+N}$$
$$=35\times \dfrac{\dfrac{0.6}{60}}{\dfrac{0.6}{60}+\dfrac{360}{18}}=0.017mm$$ of Hg