jee main chemistry important questions | Solutions jee main questions FREE

Q 11 :
A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ______ (Integer Answer)

(Given: Molar mass in g ${mol}^{- 1}$ Ethyl alcohol : 46, water : 18) [2024]

0%

(22)

$W_{C_{2} H_{5} O H} = n_{C_{2} H_{5} O H} \times M_{C_{2} H_{5} O H} = 1 mol \times 46 {g mol}^{- 1} = 46 g$

$W_{H_{2} O} = n_{H_{2} O} \times M_{H_{2} O} = 9 mol \times 18 {g mol}^{- 1} = 162 g$

$Mass percent of solute = \frac{W_{solute}}{W_{solution}} \times 100$

$= \frac{W_{C_{2} H_{5} O H}}{W_{H_{2} O} + W_{C_{2} H_{5} O H}} \times 100$

$= \frac{46}{162 + 46} \times 100 = 22.11 % \approx 22 %$

Q 12 :
Molarity (M) of an aqueous solution containing $x$ g of anhyd. ${CuSO}_{4}$ in 500 mL solution at 32°C is $2 \times 10^{- 1}$ M. Its molality will be _____ $\times 10^{- 3}$ m. (nearest integer).

[Given density of the solution = 1.25 g/mL] [2024]

0%

(164)

$W_{solution} = d_{solution} \times V_{solution} = 1.25 \frac{g}{mL} \times 500 mL = 625 g$

$n_{solute} = {Molarity}_{solution} \times V_{solution} = 2 \times 10^{- 1} M \times 0.5 L = 0.1 mol$

$W_{solute} = n_{solute} \times molar mass of solute = 0.1 mol \times 159.5 {gmol}^{- 1} = 15.95 g$

$W_{solvent} = W_{solution} - W_{solute} = 625 g - 15.95 g = 609.05 g$

$m = \frac{n_{solute} \times 1000}{W_{solvent} (in g)} = \frac{0.1 \times 1000}{609.05} m = 0.1642 m = 164 \times 10^{- 3} m$

Q 13 :
The quantity which changes with temperature is: [2024]

Molarity
Mass percentage
Molality
Mole fraction

1

2

3

4

(1)

Q 14 :
‘x’ g of NaCl is added to water in a beaker with a lid. The temperature of the system is raised from 1°C to 25°C. Which out of the following plots, is best suited for the change in the molarity (M) of the solution with respect to temperature?

[Consider the solubility of NaCl remains unchanged over the temperature range] [2025]

1

2

3

4

(2)

Density of water is maximum at 4°C. This is because from 0°C to 4°C, hydrogen bonds break and molecules come closer. After 4°C volume increases due to thermal expansion. Thus from 1°C to 4°C, volume of solution decreases and hence molarity increases. Heating the solution beyond 4°C increases its volume hence the molarity decreases.

Q 15 :
10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is : [2025]

0.2 M NaCl solution
20 M HCl solution
10 M HCl solution
Neutral solution

1

2

3

4

(2)

Final solution contains 2 mol HCl in 100 mL of solution (0.1 L solution). So concentration of final solution is $\frac{n_{HCl}}{V_{solution} (in L)} = \frac{2}{0.1} M = 20 M$

Q 16 :
20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is ______ $\times 10^{- 2}$ M. (Nearest integer) [2025]

0%

(57)

$Final concentration = \frac{M_{1} V_{1} + M_{2} V_{2}}{V_{1} + V_{2}}$

$= \frac{2 \times 20 + 0.5 \times 400}{20 + 400} M$

$= \frac{240}{420} M = 0.571 M = 57.1 \times 10^{- 2} M$

Q 17 :
Fortification of food with iron is done using ${FeSO}_{4} . 7 H_{2} O$ . The mass in grams of the ${FeSO}_{4} . 7 H_{2} O$ required to achieve 12 ppm of iron in 150 kg of wheat is _____ (Nearest integer)

[Given: Molar mass of Fe, S and O respectively are 56, 32 and 16 g ${mol}^{- 1}$ ] [2025]

0%

(9)

$ppm = \frac{w_{iron}}{w_{wheat}} \times 10^{6}$

$12 = \frac{w_{iron}}{150} \times 10^{6}$

$w_{iron} = \frac{12 \times 150}{10^{6}} kg = \frac{12 \times 150}{10^{6}} \times 1000 g = 1.8 g$

$Moles of iron = \frac{W_{iron}}{M_{iron}} = \frac{1.8}{56} mol$

${Moles of FeSO}_{4} . 7 H_{2} O = Moles of iron = \frac{1.8}{56} mol$

${Molar mass of FeSO}_{4} . 7 H_{2} O = 56 + 32 + 4 \times 16 + 7 \times 18 = 278 g/mol$

${Mass of FeSO}_{4} . 7 H_{2} O = {moles of FeSO}_{4} . 7 H_{2} O \times {molar mass of FeSO}_{4} . 7 H_{2} O$ $= \frac{1.8}{56} \times 278 g = 8.935 gm \approx 9 gm$

Q 18 :
Sea water, which can be considered as a 6 molar (6 M) solution of NaCl, has a density of 2 g ${mL}^{- 1}$ .

The concentration of dissolved oxygen ( $O_{2}$ ) in sea water is 5.8 ppm. Then the concentration of dissolved oxygen ( $O_{2}$ ) in sea water, is $x \times 10^{- 4}$ m.

x = _______. (Nearest integer)

Given: Molar mass of NaCl is 58.5 g ${mol}^{- 1}$

Molar mass of $O_{2}$ is 32 g ${mol}^{- 1}$ [2025]

0%

(2)

$(i) 6M NaCl solution means 6 mol NaCl in 1000 mL solution$

$i.e. 6 mol NaCl in 1000 mL \times 2 {g mL}^{- 1} solution$

$i.e. 6 mol NaCl in 2000 g solution$

$i.e. 6 \times 58.5 g NaCl in 2000 g solution$

$i.e. 351 g NaCl in 2000 g water.$

${(ii) ppm of O}_{2} = \frac{W_{O_{2}}}{W_{solvent}} \times 10^{6}$

$5.8 = \frac{W_{O_{2}}}{2000} \times 10^{6}$

$W_{O_{2}} = \frac{5.8 \times 2000}{10^{6}} = 0.0116 g$

$(iii) Mass of solvent in 2000 g solution (W_{solvent})$

$= W_{solution} - W_{NaCl} - W_{O_{2}}$

$= 2000 - 351 - 0.0116 = 1648.9884 g$

$Molality of oxygen (m) = \frac{W_{O_{2}} \times 1000}{M_{O_{2}} \times W_{solvent}}$

$= \frac{0.0116 \times 1000}{32 \times 1648.9884} = 2.19 \times 10^{- 4}$

Topic Question Set

Q 11 :
A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ______ (Integer Answer)

(Given: Molar mass in g ${mol}^{- 1}$ Ethyl alcohol : 46, water : 18) [2024]

0%

Q 12 :
Molarity (M) of an aqueous solution containing $x$ g of anhyd. ${CuSO}_{4}$ in 500 mL solution at 32°C is $2 \times 10^{- 1}$ M. Its molality will be _____ $\times 10^{- 3}$ m. (nearest integer).

[Given density of the solution = 1.25 g/mL] [2024]

0%

Q 13 :
The quantity which changes with temperature is: [2024]

Q 15 :
10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is : [2025]

Q 16 :
20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is ______ $\times 10^{- 2}$ M. (Nearest integer) [2025]

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Topic Question Set

Q 11 : A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ______ (Integer Answer) (Given: Molar mass in g mol-1 Ethyl alcohol : 46, water : 18) [2024]

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Q 12 : Molarity (M) of an aqueous solution containing x g of anhyd. CuSO4 in 500 mL solution at 32°C is 2×10-1 M. Its molality will be _____ ×10-3m. (nearest integer). [Given density of the solution = 1.25 g/mL] [2024]

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Q 13 : The quantity which changes with temperature is: [2024]

Q 15 : 10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is : [2025]

Q 16 : 20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is ______ ×10-2 M. (Nearest integer) [2025]

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Q 17 : Fortification of food with iron is done using FeSO4.7H2O. The mass in grams of the FeSO4.7H2O required to achieve 12 ppm of iron in 150 kg of wheat is _____ (Nearest integer) [Given: Molar mass of Fe, S and O respectively are 56, 32 and 16 g mol-1] [2025]

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Q 11 :
A solution is prepared by adding 1 mole ethyl alcohol in 9 mole water. The mass percent of solute in the solution is ______ (Integer Answer)

(Given: Molar mass in g ${mol}^{- 1}$ Ethyl alcohol : 46, water : 18) [2024]

Q 12 :
Molarity (M) of an aqueous solution containing $x$ g of anhyd. ${CuSO}_{4}$ in 500 mL solution at 32°C is $2 \times 10^{- 1}$ M. Its molality will be _____ $\times 10^{- 3}$ m. (nearest integer).

[Given density of the solution = 1.25 g/mL] [2024]

Q 13 :
The quantity which changes with temperature is: [2024]

Q 15 :
10 mL of 2 M NaOH solution is added to 20 mL of 1 M HCl solution kept in a beaker. Now, 10 mL of this mixture is poured into a volumetric flask of 100 mL containing 2 moles of HCl and made the volume upto the mark with distilled water. The solution in this flask is : [2025]

Q 16 :
20 mL of 2 M NaOH solution is added to 400 mL of 0.5 M NaOH solution. The final concentration of the solution is ______ $\times 10^{- 2}$ M. (Nearest integer) [2025]