Free Concentration Units MCQs with Answers

1. The energy released when solvent molecules surround the ions in ionic compounds is:

• A. Energy of solution
• B. Enthalpy
• C. Energy of solvation
• D. None of the above

Explanation: The explanation for this question will be added soon.

2. Which term describes a solution in which dissolved solute is in equilibrium with undissolved solute?

• A. Dilute
• B. Saturated
• C. Unsaturated
• D. Supersaturated

Explanation: A solution in which the maximum amount of solvent has been dissolved. Any more solute added will sit as crystals on the bottom of the container.

3. The essential property of a fertilizer is that is should be:

• A. Immiscible
• B. Highly soluble
• C. Insoluble
• D. Partially soluble

Explanation: There are three essential plant nutrients for healthy growth: nitrogen (N), phosphorous (P), potassium (K). Fertilisers contain one or more of these nutrients and different crops require different proportions of each of the three. For the fertiliser to be effective, it must be soluble so that it can reach the plant's roots.

4. 36 g of HCl dissolves in 100 g of solution. The density of HCl is 1.19 gcm-3. The molar mass of the HCl solution will be:

• A. 36.5 g/mol
• B. 38.0 g/mol
• C. 100 g/mol
• D. 11.73 g/mol

Explanation: Explanation:Ar of H is 1 and Ar of Cl is 35.5. Mr = 35.5 + 1 = 36.5 g/mol

5. Seawater has 5.65 x 10^-3 g of dissolved oxygen in one kilogram of water. Concentration of O2 in parts per million is

• A. 5.65
• B. 7.69
• C. 5.20
• D. 4.11

Explanation: A is correct since the solution is given asGiven: Water = 103 g(1 kg), Oxygen = 5.65 x 10-3 gRequired : Oxygen in ppm = ?Formula : Ppm = value in gram / amount of water ( solvent ) x 106Ppm = 5.65 x 10-3 / 103 x 106 = 5.65ppmB, C and D are incorrect because these are not correct values in ppm

6. Which ion is present in the highest concentration in a 2 mole/cm3 solution of sodium sulfate?

• A. The hydrogen ion, H+
• B. The hydroxide ion, OH-
• C. The sodium ion, Na+ (aq)
• D. The sulphate ion, SO4-2 (aq).

Explanation: .Na+ ions will be present in the highest concentration since there are 2 moles of Na+ in each mole of Na2SO4, so the concentration of Na+ is 4 moles/cm3. Therefore, C is the correct answer.

7. 2% solution by weight of sodium chloride solution is prepared. The molality of the solution is:

• A. 0.34 molal
• B. 0.25 molal
• C. 2 molals
• D. 0.02 mol

Explanation: 2% solution by weight means 2 grams of NaCl is dissolved per 100 grams of water. No. of moles = given mass/ molar mass = 2/58.5= 0.034Molality = no of moles / mass of solution in kg= 0.034/0.1= 0.34 Molal

8. In one molal aqueous solution of C2H3OH the mole fraction of C2H5OH is :

• A. 0.1
• B. 0.9
• C. 0.0177
• D. 1.0

Explanation: Explanation for this question will be added soon.

9. To what volume in .... must 50.0ml of 3.50M H2SO4 be diluted in order to make 2 M H2SO4?

• A. 25
• B. 60.1
• C. 87.5
• D. 93.2

Explanation: The correct option is c 87.5 mL M1V1=M2V2 Where, M1⇒ Molarity of the initial solution = 3.5 M V1⇒ Volume of the initial solution = 50 mL M2⇒ Molarity of the resultant solution i.e. after dilution = 2 M V2⇒ Volume of the resultant solution 3.5×50=2×V2 V2=3.5×502=87.5 mL Therefore, the initial solution must be diluted to 87.5 mL

10. In the laboratory standard solution is prepared in?

• A. Conical flasks
• B. Beakers
• C. Volumetric flask
• D. Measuring cylinder

Explanation: Volumetric flasks, on the other hand, are specifically designed for accurate measurement of a specific volume and are the preferred choice for preparing standard solutions.