The ore of mercury is: MCQ with Answer and Explanation

The ore of mercury is:
A. Galena
B. Magnetite
C. Bauxite
D. Cinnabar
Answer: Option D
Solution (By JKExamLibrary)
Cinnabar is HgS, the chief ore of mercury. Bauxite (Al), galena (Pb), magnetite (Fe). Mercury is extracted by roasting cinnabar in air: HgS + O₂ → Hg + SO₂.

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Practice More chemistry Questions

Question #1
A radioactive sample decays to 1/4 of its original amount in 40 days. Its half-life is:
A. 10 days
B. 40 days
C. 20 days
D. 80 days

Correct Answer: Option C


Explanation:
1/4 = (1/2)², so 2 half-lives = 40 days → half-life = 20 days. After 1 half-life 1/2 remains, after 2 half-lives 1/4.

This question belongs to: Science chemistry
Question #2
The main difference between diamond and graphite is:
A. Chemical formula
B. Carbon content
C. Arrangement of carbon atoms
D. Presence of hydrogen

Correct Answer: Option C


Explanation:
Both diamond and graphite are allotropes of carbon, having the same chemical element but different structural arrangements: diamond has a tetrahedral 3D network, graphite has layered planar structure. This leads to differing physical properties (hardness, conductivity).

This question belongs to: Science chemistry
Question #3
The valency of aluminium in Al₂O₃ is:
A. 2
B. 1
C. 3
D. 4

Correct Answer: Option C


Explanation:
Aluminium oxide: Al³⁺ and O²⁻. To balance charges, 2 Al³⁺ (total +6) combine with 3 O²⁻ (total -6). Thus valency of Al is 3. It loses three electrons. Formula determined by criss-cross method.

This question belongs to: Science chemistry