Chemical Equilibrium Class 11 MCQ Quiz With Answers

1. Reaction from which we can get back the reactants form products is called

Irreversible reaction

Reversible reaction

Endothermic reaction

Exothermic reaction

A reversible reaction is a reaction that can proceed in both the forward and reverse directions. This means that the products can react together to form the reactants again. In other words, the reaction is not completed in one direction only, but can be reversed. This is in contrast to an irreversible reaction, where the reaction proceeds only in one direction and cannot be reversed. Therefore, a reversible reaction is the correct answer because it describes a reaction that can go back to the reactants from products.

Explanation

A reversible reaction is a reaction that can proceed in both the forward and reverse directions. This means that the products can react together to form the reactants again. In other words, the reaction is not completed in one direction only, but can be reversed. This is in contrast to an irreversible reaction, where the reaction proceeds only in one direction and cannot be reversed. Therefore, a reversible reaction is the correct answer because it describes a reaction that can go back to the reactants from products.

2. The amount of reactant and product remain .................during equilibrium

Equal

Constant

Different

Semi different

During equilibrium, the amount of reactant and product remains constant. This is because the forward and reverse reactions occur at the same rate, resulting in a dynamic balance between the reactants and products. While the concentrations of reactants and products may change, the overall amount of each remains constant.

Explanation

During equilibrium, the amount of reactant and product remains constant. This is because the forward and reverse reactions occur at the same rate, resulting in a dynamic balance between the reactants and products. While the concentrations of reactants and products may change, the overall amount of each remains constant.

3. What is an acid according to Lewis concept?

Electron pair acceptor

Proton acceptor

Electron pair donor

Proton donor

According to the Lewis concept, an acid is defined as an electron pair acceptor. In this concept, acids are substances that can accept a pair of electrons to form a covalent bond. This is in contrast to the traditional definition of an acid as a proton donor. The Lewis concept expands the understanding of acids to include substances that can accept electrons, not just donate protons.

Explanation

According to the Lewis concept, an acid is defined as an electron pair acceptor. In this concept, acids are substances that can accept a pair of electrons to form a covalent bond. This is in contrast to the traditional definition of an acid as a proton donor. The Lewis concept expands the understanding of acids to include substances that can accept electrons, not just donate protons.

4. Strong conjugate base is out of these following:

Cl–

NO32-

CH3COO–

SO42-

The correct answer is CH3COO-, which is the conjugate base of acetic acid (CH3COOH). Acetic acid is a weak acid, meaning it only partially dissociates in water to form its conjugate base and a hydronium ion. The conjugate base of a weak acid is typically a weak base, and in this case, CH3COO- is a weak base. Therefore, CH3COO- is the strong conjugate base among the given options.

Explanation

The correct answer is CH3COO-, which is the conjugate base of acetic acid (CH3COOH). Acetic acid is a weak acid, meaning it only partially dissociates in water to form its conjugate base and a hydronium ion. The conjugate base of a weak acid is typically a weak base, and in this case, CH3COO- is a weak base. Therefore, CH3COO- is the strong conjugate base among the given options.

5. During a chemical equilibrium, which of the following statements is correct?

The rate of the forward reaction is greater than the backward reaction.

The rate of the backward reaction is greater than the forward reaction.

Both the forward and backward reactions occur at the same rate.

The rates of the forward and backward reactions are different.

In a state of chemical equilibrium, the rate of the forward reaction equals the rate of the backward reaction. This balance of rates means that the concentrations of the reactants and products remain constant over time, even though the reactions continue to occur.

Explanation

In a state of chemical equilibrium, the rate of the forward reaction equals the rate of the backward reaction. This balance of rates means that the concentrations of the reactants and products remain constant over time, even though the reactions continue to occur.

6. The colour change when copper sulphate is heated is

Blue to white

White to blue

Blue to pink

Pink to blue

When copper sulphate is heated, it undergoes a chemical reaction called thermal decomposition. During this reaction, the blue copper sulphate crystals lose water molecules and turn into anhydrous copper sulphate, which is white in color. Therefore, the color change observed when copper sulphate is heated is from blue to white.

Explanation

When copper sulphate is heated, it undergoes a chemical reaction called thermal decomposition. During this reaction, the blue copper sulphate crystals lose water molecules and turn into anhydrous copper sulphate, which is white in color. Therefore, the color change observed when copper sulphate is heated is from blue to white.

7. The weakest base out of the following is:

Ca(OH)2

KOH

NH4OH

NaOH

NH4OH is the weakest base out of the given options because it is formed by the weak base ammonia (NH3) reacting with water (H2O). Ammonia is a weak base because it does not completely dissociate into hydroxide ions (OH-) in water. Instead, it forms a small amount of NH4+ and OH- ions. Therefore, NH4OH has a lower concentration of hydroxide ions compared to the other options, making it the weakest base.

Explanation

NH4OH is the weakest base out of the given options because it is formed by the weak base ammonia (NH3) reacting with water (H2O). Ammonia is a weak base because it does not completely dissociate into hydroxide ions (OH-) in water. Instead, it forms a small amount of NH4+ and OH- ions. Therefore, NH4OH has a lower concentration of hydroxide ions compared to the other options, making it the weakest base.

8. Adding water to anhydrous copper sulphate is a ...............change

Endothermic

Exothermic

Both

None

When water is added to anhydrous copper sulphate, a chemical reaction takes place where the anhydrous copper sulphate combines with water molecules to form hydrated copper sulphate. This reaction releases energy in the form of heat, making it an exothermic change.

Explanation

When water is added to anhydrous copper sulphate, a chemical reaction takes place where the anhydrous copper sulphate combines with water molecules to form hydrated copper sulphate. This reaction releases energy in the form of heat, making it an exothermic change.

9. The pH of a solution of hydrochloric acid is 4. What is the molarity of the solution?

0.4

0.0001

0.04

4.0

The molarity of a solution is a measure of the concentration of a solute in a solution. In this case, the pH of the solution is given as 4, which indicates that the concentration of H+ ions in the solution is 10^-4 M. Since hydrochloric acid (HCl) is a strong acid that dissociates completely in water, the concentration of HCl in the solution is also 10^-4 M. Therefore, the molarity of the solution is 0.0001 M.

Explanation

The molarity of a solution is a measure of the concentration of a solute in a solution. In this case, the pH of the solution is given as 4, which indicates that the concentration of H+ ions in the solution is 10^-4 M. Since hydrochloric acid (HCl) is a strong acid that dissociates completely in water, the concentration of HCl in the solution is also 10^-4 M. Therefore, the molarity of the solution is 0.0001 M.

10. The solubility of Ca₃(PO₄)₂ in water is y mol/L. The solubility product will be

36 y4

6y²

108 y5

64 y5

The solubility product (Ksp) is a measure of the equilibrium concentration of the ions in a saturated solution. For the compound Ca3(PO4)2, it dissociates into 3 Ca2+ ions and 2 PO4 3- ions. The solubility of Ca3(PO4)2 in water is y mol/L, which means that the concentration of Ca2+ ions and PO4 3- ions in the saturated solution is also y mol/L. The solubility product is calculated by multiplying the concentrations of the ions raised to their stoichiometric coefficients. In this case, (y^3)(y^2) = y^5, so the correct answer is 108 y5.

Explanation

The solubility product (Ksp) is a measure of the equilibrium concentration of the ions in a saturated solution. For the compound Ca3(PO4)2, it dissociates into 3 Ca2+ ions and 2 PO4 3- ions. The solubility of Ca3(PO4)2 in water is y mol/L, which means that the concentration of Ca2+ ions and PO4 3- ions in the saturated solution is also y mol/L. The solubility product is calculated by multiplying the concentrations of the ions raised to their stoichiometric coefficients. In this case, (y^3)(y^2) = y^5, so the correct answer is 108 y5.