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The s-Block Elements JEE Main MCQ & Practice Questions

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The s-Block Elements Revision Guide for JEE Main Chemistry

The s-Block Elements is part of JEE Main Chemistry preparation. A strong revision plan should combine concept review with exam-style questions so that definitions, relationships, calculations and exceptions are recalled accurately.

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Important Topics

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  • Important equations or relationships
  • Common applications and examples
  • Frequently confused concepts
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  • Error review and targeted revision

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Top 20 The s-Block Elements MCQs with Answers

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JEE Main Chemistry · The s-Block Elements · Very Hard

1. The general valence-shell configuration of alkali metals is:

  • A. ns2np1
  • B. ns2np6
  • C. ns1
  • D. ns2
Answer: C
Explanation: Group 1 elements possess one electron in the outermost s orbital.

JEE Main Chemistry · The s-Block Elements · Very Hard

2. The general valence-shell configuration of alkaline-earth metals is:

  • A. ns2np6
  • B. ns2
  • C. ns1
  • D. ns2np2
Answer: B
Explanation: Group 2 elements have two valence electrons in the outermost s orbital.

JEE Main Chemistry · The s-Block Elements · Very Hard

3. The most common oxidation state of alkali metals is:

  • A. +1
  • B. +2
  • C. -1
  • D. +3
Answer: A
Explanation: Alkali metals lose their single valence electron to form M+ ions.

JEE Main Chemistry · The s-Block Elements · Very Hard

4. The most common oxidation state of alkaline-earth metals is:

  • A. +1
  • B. +3
  • C. -2
  • D. +2
Answer: D
Explanation: Group 2 metals lose two valence electrons to form M2+ ions.

JEE Main Chemistry · The s-Block Elements · Very Hard

5. The first ionisation enthalpy of alkali metals generally:

  • A. Remains constant
  • B. Becomes zero
  • C. Decreases down the group
  • D. Increases down the group
Answer: C
Explanation: Atomic size and shielding increase down the group, weakening attraction for the valence electron.

JEE Main Chemistry · The s-Block Elements · Very Hard

6. The atomic radius of alkali metals generally:

  • A. First increases then becomes zero
  • B. Increases down the group
  • C. Decreases down the group
  • D. Remains constant
Answer: B
Explanation: Each successive element has an additional electron shell.

JEE Main Chemistry · The s-Block Elements · Very Hard

7. Among alkali metals, lithium has the highest:

  • A. Ionisation enthalpy
  • B. Atomic radius
  • C. Metallic character
  • D. Reducing power in aqueous solution
Answer: A
Explanation: Lithium is the smallest alkali metal and holds its valence electron most strongly.

JEE Main Chemistry · The s-Block Elements · Very Hard

8. The strongest reducing agent among alkali metals in aqueous solution is:

  • A. Sodium
  • B. Potassium
  • C. Caesium
  • D. Lithium
Answer: D
Explanation: Lithium's very high hydration enthalpy makes its standard reduction potential exceptionally negative.

JEE Main Chemistry · The s-Block Elements · Very Hard

9. The strongest reducing agent among alkali metals in the gaseous state is approximately:

  • A. Sodium
  • B. Magnesium
  • C. Caesium
  • D. Lithium
Answer: C
Explanation: In the gas phase, lower ionisation enthalpy down the group favours electron loss.

JEE Main Chemistry · The s-Block Elements · Very Hard

10. Alkali metals are stored under kerosene because they:

  • A. React with nitrogen only
  • B. React rapidly with air and moisture
  • C. Dissolve in kerosene chemically
  • D. Are noble metals
Answer: B
Explanation: Kerosene isolates them from oxygen and water.

JEE Main Chemistry · The s-Block Elements · Very Hard

11. Lithium reacts with nitrogen directly to form:

  • A. Li3N
  • B. LiN3
  • C. Li2N
  • D. LiNO3
Answer: A
Explanation: Lithium uniquely forms stable lithium nitride, Li3N, among alkali metals.

JEE Main Chemistry · The s-Block Elements · Very Hard

12. The oxide formed predominantly when lithium burns in oxygen is:

  • A. Li2O2
  • B. LiO2
  • C. LiO
  • D. Li2O
Answer: D
Explanation: Small Li+ stabilises the compact oxide ion O2-.

JEE Main Chemistry · The s-Block Elements · Very Hard

13. Sodium burns in excess oxygen mainly to form:

  • A. NaO2
  • B. Na2O3
  • C. Na2O2
  • D. Na2O
Answer: C
Explanation: Sodium commonly forms the peroxide Na2O2.

JEE Main Chemistry · The s-Block Elements · Very Hard

14. Potassium burns in excess oxygen mainly to form:

  • A. K2O3
  • B. KO2
  • C. K2O
  • D. K2O2 only
Answer: B
Explanation: Large K+ stabilises the large superoxide ion O2-.

JEE Main Chemistry · The s-Block Elements · Very Hard

15. The stability of superoxides increases down Group 1 because:

  • A. Larger cations better stabilise the large superoxide ion
  • B. Ionisation enthalpy increases
  • C. Cation radius decreases
  • D. Electronegativity increases
Answer: A
Explanation: Large low-charge-density cations favour larger anions such as O2-.

JEE Main Chemistry · The s-Block Elements · Very Hard

16. Alkali metals react with water to produce:

  • A. Metal oxide and oxygen
  • B. Metal hydride and oxygen
  • C. Metal peroxide only
  • D. Metal hydroxide and hydrogen
Answer: D
Explanation: 2M + 2H2O -> 2MOH + H2.

JEE Main Chemistry · The s-Block Elements · Very Hard

17. The reactivity of alkali metals with water generally:

  • A. Remains constant
  • B. Is highest for lithium only
  • C. Increases down the group
  • D. Decreases down the group
Answer: C
Explanation: Ionisation enthalpy decreases and metallic character increases down the group.

JEE Main Chemistry · The s-Block Elements · Very Hard

18. Alkali-metal hydroxides are generally:

  • A. Amphoteric only
  • B. Strong bases
  • C. Weak acids
  • D. Neutral
Answer: B
Explanation: They ionise extensively in water to furnish OH- ions.

JEE Main Chemistry · The s-Block Elements · Very Hard

19. The basic strength of alkali-metal hydroxides generally:

  • A. Increases down the group
  • B. Decreases down the group
  • C. Remains constant
  • D. Is zero for CsOH
Answer: A
Explanation: Increasing ionic character and solubility make hydroxides more strongly basic down the group.

JEE Main Chemistry · The s-Block Elements · Very Hard

20. Lithium hydroxide is less basic than CsOH mainly because Li-O bonding has:

  • A. No ionic character
  • B. Metallic character
  • C. Hydrogen bonding only
  • D. Greater covalent character
Answer: D
Explanation: Small Li+ strongly polarises OH-, increasing covalent character.

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The s-Block Elements Practice Tests

The s-Block Elements Frequently Asked Questions

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