Test: Expressing Concentration of Solutions (NCERT) - NEET MCQ

Mass of solution = Mass of C₆H₆ + Mass of CCl₄
= 22 + 122 = 144 g
Mass % of CCl₄ = = 84.72%

No. of moles of glucose = 10/180 = 0.0555 mol
No. of moles of water = 90/18 = 5 mol
Number of moles of solution = 5.0555 mol
Mole fraction of glucose = No. of moles of glucose/No. of moles of solution = 0.0555/5.0555 = 0.01

Mass of solute is obtained by multiplying % weight with mass of solvent and obtaining an answer divided by 100.
Mass of solute in 200g of 30% solution can be obtained as follows:
30% by weight indicates 30g of solute is present in 100g of solvent so 60g of solute will be present in 200g of solution.
20% by weight indicates 20g of solute is present in 100g of solvent so 60g of solute will be present in 300g of solution
So on mixing these both solutions, mass of solute is 60g +60g =120g
Mass of solution on mixing is 200g +300g =500g
Percent of solute can be obtained as follows:

24% percentage of solute in the final solution.

ppm = 

= 10.4 ppm

Mass of C₂H₅OH = 85 g
Molar mass of C₂H₅OH = 46 g/mol
nC₂H₅OH = 85/46 = 1.85 mol
Mass of water = 100 - 85 = 15 g
nH₂O = 15/18 = 0.833 mol

No. of moles of NaOH = 10/40 = 0.25 mol

V₁ = 30 mL, M₁ = 0.5 M, V₂ = 500 mL, M₂ = ?,
M₁V₁ = M₂V₂
0.5 x 30 = M₂ × 500 or M₂ = 0.03 M

NaCl → Na⁺ + Cl⁻
No. of moles of Na⁺ ions = 0.025
No. of Na⁺ ions = 0.025 x 6.023 x 10²³ = 1.505 × 10²²

No. of moles of NaOH

Mass of NaOH = 40 × 0.125 = 5g

Molarity of Na₂CO₃ solution
= 2.65/106 × 1000/250 = 0.1 M
10mL of this solution is diluted to 500mL
M₁V₁ = M₂V₂ 
0.1 × 10 = M₂ × 500
⇒ M₂ = 0.002M

Mass of solute taken = 120g
Molecular mass of solute = 60u
Mass of solvent = 1000g
Density of solution = 1.15g/mL
Total mass of solution = 1000 + 120 = 1120g

Mass of the solution = 100g
Mass of glucose = 10g, Mass of water = 90 g
No. of moles of glucose = 10/180 = 0.0555mol
No. of moles of water = 90/18 = 5 mol
Molality = No. of moles of solute/Mass of solvent in kg
= 0.0555mol/0.0090kg = 0.617m

Molality = no of moles of solute/mass of solvent in kg
Molar mass of water = 18 g
Mass of water = 648 g
No of moles of water = 648/18 = 36 mol

Mass of solvent = 1000 g
Molar mass of urea (NH₂CONH₂) = 60gmol⁻¹
0.25 mole of urea = 0.25 × 60 = 15g
Total mass of solution = 100 + 15 = 1.015kg
1.015 kg of solution contain urea = 15g
2.5 kg of solution = 

Molarity of a solution is defined as the number of moles of solute dissolved per litre of solution. Since volume depends on temperature and changes with change in temperature, therefore, the molarity will also change with change in temperature. On the other hand, mass does not change with change in temperature, and therefore, concentration terms such as mass percentage, mole fraction and molality which do not involve volume are independent of temperature.