The hardest natural substance is: MCQ with Answer and Explanation

The hardest natural substance is:
A. Quartz
B. Graphite
C. Fullerene
D. Diamond
Answer: Option D
Solution (By JKSSB Mock Tests)
Diamond, with its tetrahedral covalent network, is the hardest known natural material (Mohs 10). Graphite is soft; quartz is SiO₂, hardness 7.

Discuss this Question (0)

No comments yet. Be the first to start the discussion!

Practice More chemistry Questions

Question #1
If the volume of a gas is doubled at constant temperature, its pressure will:
A. Double
B. Halve
C. Become four times
D. Remain the same

Correct Answer: Option B


Explanation:
According to Boyle's Law (P₁V₁ = P₂V₂), pressure and volume are inversely proportional at constant temperature. If the volume is doubled (V₂ = 2V₁), the pressure must be halved (P₂ = P₁/2) to keep the product constant. This demonstrates the inverse relationship between P and V.

This question belongs to: Science chemistry
Question #2
The element with highest ionization energy in the second period is:
A. Fluorine
B. Lithium
C. Beryllium
D. Neon

Correct Answer: Option D


Explanation:
Ionization energy generally increases across a period due to increasing nuclear charge. Neon (noble gas) has the highest ionization energy in period 2 because of its stable filled octet (2s²2p⁶). Removing an electron requires enormous energy. Fluorine is next highest. Lithium has lowest. Noble gases have very high IE values, making them inert.

This question belongs to: Science chemistry
Question #3
Which of the following pairs are isobars?
A. ¹²C and ¹⁴C
B. ³⁵Cl and ³⁷Cl
C. ¹H and ²H
D. ⁴⁰Ar and ⁴⁰Ca

Correct Answer: Option D


Explanation:
Isobars are atoms of different elements with the same mass number but different atomic numbers. ⁴⁰Ar (atomic number 18) and ⁴⁰Ca (atomic number 20) both have mass number 40. Options A and D are isotopes (same element, different mass number). Option C are isotopes of hydrogen. Isobars have different chemical properties because of different proton numbers. Example: ¹⁴C and ¹⁴N.

This question belongs to: Science chemistry