All Free Chemistry MCQs with Answers

• A. 9
• B. 6.5-7
• C. 8
• D. 12

Explanation: Fresh milk is slightly acidic, with a normal pH close to 6.5 to 6.7, mainly because of dissolved carbon dioxide, phosphates and lactic…

• A. (a) Increases as the reaction proceeds.
• B. (b) Decreases as the reaction proceeds.
• C. (c) Remains the same as the reaction proceeds.
• D. (d) May decrease or increase as the reaction proceeds.

Explanation: The rate of a reaction typically decreases as the reaction proceeds. At the beginning of a reaction, there are more reactants available…

• A. (a) Increases the rate of forward reaction only.
• B. (b) Increases the rate of reverse reaction.
• C. (c) Increases the rate of forward but decreases the rate of backward reaction.
• D. (d) Increases the rate of forward as well as backward reaction equally.

Explanation: The correct answer for the effect of a catalyst on a reaction's rate is:(c) Increases the rate of forward but decreases the rate of…

• A. Time
• B. (b) Concentration of the reactant
• C. Temperature
• D. (d) Concentration of the product.

Explanation: Types of rates of reaction)The correct answer for the factor influencing the specific rate constant of a first-order reaction is:(c)…

• A. (a) The activation energy of the reaction increases
• B. (b) Concentration of the reacting molecules increases
• C. (c) Collision frequency increases
• D. (d) None of these

Explanation: The correct answer is:(c) Collision frequency increasesHere's why the other options are incorrect:(a) The activation energy of the…

• A. Molecularity
• B. (a) Order of reaction
• C. (d) Average of reaction
• D. (c) Rate of reaction

Explanation: The correct answer is:(b) Order of reactionHere's the breakdown of why the other options are incorrect:(a) Molecularity: While the term…

• A. Only products
• B. Composition of reacting substances and products
• C. Only reacting substances
• D. None of above

Explanation: The law of mass action is a fundamental principle in chemistry that relates the rate of a chemical reaction to the concentrations of the…

• A. Its temperature is more than critical temperature
• B. Its pressure is more than critical pressure
• C. Its pressure is more than critical pressure but temperature is less than criticaltemperature
• D. It cannot be liquefied at any value of P and T.

Explanation: An ideal gas is a theoretical concept that obeys the ideal gas law (PV = nRT) perfectly.

• A. Mg + 2HCI→ MgCI + H2
• B. MgO + 2HCI→ MgCI2+ H2O
• C. Cu +4HNO3→ Cu(NO3)2+2H2O+2NO3
• D. 2Mg + O2→2MgO

Explanation: Both Mg and O already have fixed oxidation states (0) and combine to form MgO without any change in oxidation states.Not a redox reaction.

• A. Free energy change
• B. Van Der Waals equation
• C. Arrhenius equation
• D. Kinetic equation

Explanation: The effect of temperature on reaction rate is described by the Arrhenius equation.It shows that increasing temperature increases the rate…

• A. Increases as the reaction proceeds
• B. Decreases as the reaction proceeds
• C. Remains the same as the reaction proceeds
• D. May decrease or increase as the reaction proceeds

Explanation: The rate of reaction is dependent on the concentration of reactants. The rate of a reaction decreases as time progresses.

• A. Pressure
• B. Temperature
• C. Effective collision
• D. Ineffective collision

Explanation: Activated complexes are formed as a result of effective collisions, and the term is used to refer to the state of the molecule when the…

• A. Ultraviolet radiations
• B. Visible radiations
• C. Infrared radiations
• D. All of these

Explanation: This method is applicable if a reactant or a product absorbs ultraviolet, visible or infrared radiations.

• A. Average K. E of the molecules
• B. Potential energy of the molecules
• C. Free energy of the molecules
• D. Activation energy of the molecules

Explanation: Activation energy is the minimum energy that the reactants must have to be converted into products.

• A. by increasing temperature
• B. using a suitable catalyst
• C. by an increase in activation energy
• D. by increasing concentration of reactants

Explanation: Activation energy is inversely proportional to the rate of the reaction.

• A. Increases the rate of the forward reaction only
• B. Increases the rate of both forward and reverse reactions
• C. Changes the equilibrium position
• D. Increases the rate of the reverse reaction only

Explanation: A catalyst increases the rate of both forward and reverse reaction, making the system reach equilibrium faster.

• A. The temperature of the reaction
• B. The concentration of reactants
• C. The concentration of products
• D. The presence of a catalyst

Explanation: In a zero-order reaction, the rate of reaction is independent of the concentration of reactants.

• A. Initial Conc of Products
• B. Initial Conc of Reactants
• C. Ions
• D. Radicals

Explanation: Zero-order reactions are unique because their reaction rate remains constant and does not depend on the concentration of reactants.

• A. Negative
• B. Zero
• C. Equal
• D. Positive

Explanation: When considering reaction kinetics, the average rate of reaction over a given time interval is calculated as the change in concentration…

• A. Area under the curve
• B. Calculating the length of the curve
• C. Drawing a tangent to the curve
• D. All of these options are correct

Explanation: The area under the graph does not give the slope. Calculating the length of the curve does not give the slope.