Unit 4-5 MCQ

Front

What is the mole concept in chemistry?

Back

The mole is a unit of measurement used to express the amount of a substance. One mole contains approximately 6.022 x 10^23 particles (atoms, molecules, ions, etc.).

Front

Define a limiting reactant in a chemical reaction.

Back

A limiting reactant is the substance that is completely consumed in a chemical reaction, limiting the amount of product that can be formed.

Front

What is the significance of reaction temperature in chemical reactions?

Back

Temperature affects the rate of chemical reactions; generally, increasing temperature increases reaction rates due to higher kinetic energy of molecules.

Front

Explain the concept of reaction rate.

Back

Reaction rate is the speed at which reactants are converted into products in a chemical reaction, often expressed in terms of concentration change over time.

Front

What does it mean for a reaction to be first order with respect to a reactant?

Back

A reaction is first order with respect to a reactant if the rate of reaction is directly proportional to the concentration of that reactant.

Front

What is the role of a catalyst in a chemical reaction?

Back

A catalyst is a substance that increases the rate of a chemical reaction without being consumed in the process.

Front

Define an intermediate in a chemical reaction mechanism.

Back

An intermediate is a transient species formed during the reaction that is not a reactant or product but is involved in the reaction pathway.

Front

What is the difference between exothermic and endothermic reactions?

Back

Exothermic reactions release heat to the surroundings, while endothermic reactions absorb heat from the surroundings.

Front

What is the purpose of a balanced chemical equation?

Back

A balanced chemical equation ensures that the number of atoms for each element is conserved in a reaction, reflecting the law of conservation of mass.

Front

Explain the concept of collision theory in chemical reactions.

Back

Collision theory states that for a reaction to occur, reactant particles must collide with sufficient energy and proper orientation.