A molecule is defined as the smallest particle of a substance that can exist independently and retain its: MCQ with Answer and Explanation

A molecule is defined as the smallest particle of a substance that can exist independently and retain its:
A. Mass
B. Volume
C. Chemical properties
D. Physical state
Answer: Option C
Solution (By JKExamLibrary)
A molecule is a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction while retaining the composition and chemical properties of that substance. For example, H₂O molecule shows properties of water. Atoms (like He) can also be independent, but a molecule of an element (O₂) or compound retains identity.

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Practice More chemistry Questions

Question #1
Positive catalysts work by:
A. Increasing activation energy
B. Consuming reactants
C. Decreasing activation energy
D. Changing equilibrium

Correct Answer: Option C


Explanation:
Catalysts lower activation energy, providing an easier pathway, thus increasing reaction rate. They do not affect equilibrium constant or get consumed.

This question belongs to: Science chemistry
Question #2
Rusting of iron is accelerated in:
A. Vacuum
B. Dry air
C. Saline water
D. Pure water without air

Correct Answer: Option C


Explanation:
Saline water (containing NaCl) increases the electrical conductivity of the water, accelerating the electrochemical process of rusting. This is why ships and coastal structures rust faster. Dry air and vacuum have no moisture; pure water without dissolved oxygen slows rusting.

This question belongs to: Science chemistry
Question #3
In a redox reaction:
A. Oxidation and reduction occur simultaneously.
B. Neither oxidation nor reduction occurs.
C. Only reduction occurs.
D. Only oxidation occurs.

Correct Answer: Option A


Explanation:
Redox stands for reduction-oxidation. In any redox reaction, oxidation (loss of electrons) and reduction (gain of electrons) always occur simultaneously. The substance oxidized acts as a reducing agent, and the substance reduced acts as an oxidizing agent. One cannot happen without the other.

This question belongs to: Science chemistry