Assertion (A): Sodium chloride conducts electricity in its molten state. Reason (R): In the molten state, the ions are free to move and carry charge. MCQ with Answer and Explanation

Assertion (A): Sodium chloride conducts electricity in its molten state. Reason (R): In the molten state, the ions are free to move and carry charge.
A. A is false but R is true.
B. Both A and R are true and R is the correct explanation of A.
C. Both A and R are true but R is NOT the correct explanation of A.
D. A is true but R is false.
Answer: Option B
Solution (By JKSSB Mock Tests)
Sodium chloride is an ionic compound. In the solid state, its Na+ and Cl- ions are held tightly in a crystal lattice and cannot move, so it doesn't conduct. When melted, the lattice breaks down, and the ions become mobile. These free-moving ions carry the electric current, making it a good conductor.

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Practice More chemistry Questions

Question #1
Consider the following statements: 1. Chromatography separates components based on differential adsorption. 2. The component that is more strongly adsorbed moves faster. Which statement(s) is/are correct?
A. Both 1 and 2
B. 2 only
C. Neither 1 nor 2
D. 1 only

Correct Answer: Option D


Explanation:
Chromatography is an advanced technique used to separate mixtures based on the differential adsorption of components onto a stationary phase. The component that is more strongly adsorbed to the stationary phase moves slower, not faster. Therefore, only statement 1 is correct, making option A the right choice.

This question belongs to: Science chemistry
Question #2
Which of the following is a thermoplastic?
A. Vulcanized rubber
B. Polythene
C. Melamine
D. Bakelite

Correct Answer: Option B


Explanation:
Polythene (polyethylene) softens on heating and can be remolded, thus thermoplastic. Bakelite and melamine are thermosetting (cannot be remolded). Vulcanized rubber is also thermoset due to cross-linking. Thermoplastics have linear or branched chains, no cross-links.

This question belongs to: Science chemistry
Question #3
The bond in HCl is best described as:
A. Pure covalent
B. Coordinate
C. Pure ionic
D. Polar covalent

Correct Answer: Option D


Explanation:
Hydrogen chloride is a polar covalent bond because the shared electron pair is unequally shared due to the higher electronegativity of chlorine (3.0) compared to hydrogen (2.1). The bond has a dipole moment, making HCl molecule polar. In water, HCl ionizes to H⁺ and Cl⁻, but the gaseous molecule is covalent. Pure ionic bonds exist in compounds like NaCl where electronegativity difference is large (>1.7).

This question belongs to: Science chemistry