Chemistry · Physics

Thermodynamics and Chemical Kinetics

1,132 Questions

Thermodynamics and chemical kinetics are crucial branches of physical chemistry. This area focuses on energy transformations, reaction rates, equilibrium constants, and catalysts. These topics carry significant weight in competitive science and engineering examinations.

Enthalpy and energyChemical equilibriumEntropy conceptsReaction kinetics and catalysts

Thermodynamics and Chemical Kinetics Questions

Multiple choice

If temperature is kept constant during the reaction a process, it is called

  1. adiabatic

  2. isobaric

  3. isochoric

  4. isothermal

Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

An isothermal process is one where temperature remains constant throughout. In thermodynamics, different prefixes indicate different constant conditions: iso-same, thermal-temperature (isothermal), baric-pressure (isobaric), choric-volume (isochoric). Adiabatic means no heat exchange, not constant temperature.

Multiple choice

Enzymes promote chemical reaction by

  1. reducing the activation energies

  2. causing the release of heat which acts as a primer

  3. increasing molecular motion

  4. changing the free energy difference between substrate and product
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Enzymes are biological catalysts that speed up chemical reactions by lowering the activation energy required for the reaction to proceed. They provide an alternative reaction pathway with a lower energy barrier, allowing reactions to occur faster under physiological conditions. Enzymes do not change the free energy difference between reactants and products, do not primarily work by releasing heat, and do not just increase molecular motion.

Multiple choice

Which of the following statements is/are false?

a. At a receptor, the energy provided by a stimulus sets off a chemical reaction which converts the energy of stimulus into electrical impulse. b. Animals react to stimuli in many different ways because they have a nervous system but no endocrine system involving hormones. c. Amoeba tend to aggregate in moderately warm water which is their stimuli to heat.

  1. Only a

  2. Only a and b

  3. Only b

  4. Only b and c

  5. Only c
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

This is the correct option as this statement is false. Animals react to stimuli in many different ways because they have a nervous system and an endocrine system involving hormones.

Multiple choice

Which of the following statements describes an endothermic change?

  1. Changes in which heat is liberated.

  2. Changes which take place in few seconds.

  3. Changes which take days, months, and years to occur.

  4. Changes in which energy is absorbed.

  5. Changes which occur at fixed interval of time.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

It is an endothermic change.

Multiple choice

Which of the following statements does not describe physical change?

  1. Composition of substance remains same.

  2. No new substance is formed.

  3. Chemical properties of a substance change.

  4. Physical changes are reversible.

  5. Expansion of iron on heating is an example of physical change.
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Yes, it is the correct answer as properties are changed in the chemical changes, not physical changes.

Multiple choice

What happens during a chemical change?

  1. There is no change in composition.

  2. A substance combines with other to form a new substance.

  3. There is no change in molecular composition.

  4. Energy is always given out.

  5. There is no change in colour.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Chemical change lead to the formation of new substance.

Multiple choice

Which group of changes include only chemical changes?

  1. Metabolism of food in the body, electroplating a metal and crushing a can

  2. Mixing an acid and a base, baking a cake and breaking a glass

  3. Mixing an acid and a base, baking a cake, and electroplating a metal

  4. Electroplating a metal, baking a cake and crushing a can

  5. Metabolism of food in the body, burning a candle and electroplating a metal
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

All are the types of chemical changes.

Multiple choice

The function of a catalyst in a reaction is to

  1. decrease the rate of the reaction

  2. increase the rate of the reaction

  3. increase the pressure of the reactants

  4. decrease the pressure of the reactants
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

A catalyst is a substance that increases the rate of a chemical reaction by providing an alternative pathway with a lower activation energy, without being consumed in the process.