s-Block Elements MCQs – Alkali and Alkaline Earth Metals
s-Block Elements MCQs – Alkali and Alkaline Earth Metals (Class 11 Chemistry)
Course: CBSE Class 11 Chemistry – MCQs with Answers and Explanations
Section: Inorganic Chemistry – MCQ Titles
The following 50 Multiple Choice Questions (MCQs) are strictly based on the NCERT chapter “The s-Block Elements”, covering alkali metals (Group 1) and alkaline earth metals (Group 2). The questions are arranged section-wise and supported with clear, concept-clearing explanations, making them ideal for CBSE Class 11 board exam preparation.
Section A: Introduction to s-Block Elements
1. s-Block elements are those in which the last electron enters the
A. p-orbital
B. d-orbital
C. f-orbital
D. s-orbital
Answer: D
Explanation: s-Block elements have their valence electrons in s-orbitals.
2. s-Block elements belong to
A. Groups 1 and 2
B. Groups 2 and 13
C. Groups 13 and 14
D. Groups 17 and 18
Answer: A
Explanation: Alkali metals (Group 1) and alkaline earth metals (Group 2) form the s-block.
3. The most electropositive elements are
A. halogens
B. noble gases
C. alkali metals
D. transition metals
Answer: C
Explanation: Alkali metals readily lose electrons and are highly electropositive.
Section B: Alkali Metals – General Characteristics
4. Alkali metals have general electronic configuration
A. ns²
B. ns¹
C. ns²np¹
D. ns²np⁶
Answer: B
Explanation: One valence electron in s-orbital makes them highly reactive.
5. Alkali metals are stored under kerosene oil because they
A. are radioactive
B. react with oxygen and moisture
C. sublime easily
D. are poisonous
Answer: B
Explanation: They react vigorously with air and water.
6. Which alkali metal has the smallest atomic radius?
A. Sodium
B. Lithium
C. Potassium
D. Cesium
Answer: B
Explanation: Atomic size increases down the group.
7. Which alkali metal shows anomalous behaviour?
A. Sodium
B. Potassium
C. Lithium
D. Rubidium
Answer: C
Explanation: Lithium shows anomalies due to its small size and high polarising power.
Section C: Physical Properties of Alkali Metals
8. Alkali metals are
A. hard solids
B. soft metals
C. brittle metals
D. non-metals
Answer: B
Explanation: They can be cut with a knife due to softness.
9. Melting points of alkali metals
A. increase down the group
B. decrease down the group
C. remain constant
D. increase across a period
Answer: B
Explanation: Metallic bonding weakens with increasing atomic size.
10. Which alkali metal has the lowest melting point?
A. Sodium
B. Lithium
C. Cesium
D. Potassium
Answer: C
Explanation: Cesium has the largest atomic size.
Section D: Chemical Properties of Alkali Metals
11. Alkali metals react with water to form
A. acidic solution
B. neutral solution
C. basic solution
D. salt only
Answer: C
Explanation: Metal hydroxides formed are strongly basic.
12. Reaction of sodium with water produces
A. NaOH and H₂
B. Na₂O and H₂
C. Na₂O₂
D. NaH
Answer: A
Explanation: Sodium forms sodium hydroxide and hydrogen gas.
13. Alkali metals form which type of oxides?
A. acidic
B. amphoteric
C. basic
D. neutral
Answer: C
Explanation: Their oxides dissolve in water to give bases.
14. Lithium forms
A. oxide only
B. peroxide
C. superoxide
D. all of these
Answer: A
Explanation: Due to small size, lithium forms only Li₂O.
15. Sodium mainly forms
A. oxide
B. peroxide
C. superoxide
D. hydroxide only
Answer: B
Explanation: Sodium commonly forms Na₂O₂.
16. Potassium forms
A. oxide
B. peroxide
C. superoxide
D. hydroxide
Answer: C
Explanation: Larger alkali metals stabilise superoxides.
Section E: Uses of Alkali Metals
17. Sodium is used in
A. nuclear reactors
B. street lighting
C. making alloys
D. all of these
Answer: D
Explanation: Sodium has many industrial applications.
18. Lithium is used in
A. batteries
B. fertilisers
C. pigments
D. detergents
Answer: A
Explanation: Lithium-ion batteries are widely used.
Section F: Alkaline Earth Metals – General Characteristics
19. Alkaline earth metals belong to
A. Group 1
B. Group 2
C. Group 13
D. Group 14
Answer: B
Explanation: Group 2 elements are called alkaline earth metals.
20. General electronic configuration of alkaline earth metals is
A. ns¹
B. ns²
C. ns²np¹
D. ns²np⁶
Answer: B
Explanation: Two valence electrons make them divalent.
21. Which alkaline earth metal shows anomalous behaviour?
A. Calcium
B. Magnesium
C. Beryllium
D. Strontium
Answer: C
Explanation: Beryllium shows anomalous behaviour due to small size.
Section G: Physical Properties of Alkaline Earth Metals
22. Alkaline earth metals are
A. softer than alkali metals
B. harder than alkali metals
C. non-metals
D. brittle solids
Answer: B
Explanation: They are harder due to stronger metallic bonding.
23. Atomic radius of alkaline earth metals
A. decreases down the group
B. remains constant
C. increases down the group
D. increases across the period
Answer: C
Explanation: Additional shells increase atomic size.
24. Which has the highest ionisation enthalpy in Group 2?
A. Be
B. Mg
C. Ca
D. Ba
Answer: A
Explanation: Smaller size leads to higher ionisation enthalpy.
Section H: Chemical Properties of Alkaline Earth Metals
25. Alkaline earth metals generally form
A. +1 ions
B. +2 ions
C. +3 ions
D. −1 ions
Answer: B
Explanation: Loss of two electrons gives stable configuration.
26. Oxides of alkaline earth metals are
A. acidic
B. amphoteric
C. basic
D. neutral
Answer: C
Explanation: Their oxides form hydroxides with water.
27. Which oxide is amphoteric?
A. MgO
B. CaO
C. BeO
D. BaO
Answer: C
Explanation: Beryllium oxide is amphoteric.
28. Hydroxides of alkaline earth metals
A. decrease in basicity down the group
B. increase in basicity down the group
C. remain neutral
D. are acidic
Answer: B
Explanation: Solubility and basic strength increase down the group.
29. Which hydroxide is least soluble in water?
A. Mg(OH)₂
B. Ca(OH)₂
C. Sr(OH)₂
D. Ba(OH)₂
Answer: A
Explanation: Solubility increases down the group.
Section I: Salts of s-Block Elements
30. Sodium carbonate is commonly known as
A. washing soda
B. baking soda
C. bleaching powder
D. caustic soda
Answer: A
Explanation: Na₂CO₃·10H₂O is washing soda.
31. Baking soda is
A. Na₂CO₃
B. NaOH
C. NaHCO₃
D. NaCl
Answer: C
Explanation: Sodium hydrogen carbonate is baking soda.
32. Plaster of Paris is chemically
A. CaSO₄·2H₂O
B. CaSO₄·½H₂O
C. CaCO₃
D. CaO
Answer: B
Explanation: It is calcium sulphate hemihydrate.
33. Cement is mainly a mixture of
A. calcium carbonate and silica
B. calcium silicates and aluminates
C. calcium oxide only
D. calcium sulphate only
Answer: B
Explanation: Cement contains complex calcium silicates.
Section J: Biological Importance
34. Sodium and potassium ions are important for
A. bone formation
B. nerve impulse transmission
C. blood clotting
D. enzyme inhibition
Answer: B
Explanation: They maintain membrane potential in nerves.
35. Calcium is essential for
A. photosynthesis
B. bone and teeth formation
C. respiration
D. digestion only
Answer: B
Explanation: Calcium provides structural support to bones and teeth.
36. Magnesium is a constituent of
A. haemoglobin
B. chlorophyll
C. insulin
D. vitamins
Answer: B
Explanation: Magnesium is central metal ion in chlorophyll.
Section K: Comparative Properties
37. Reactivity of alkali metals
A. decreases down the group
B. increases down the group
C. remains constant
D. increases across the period
Answer: B
Explanation: Ionisation enthalpy decreases down the group.
38. Which is more reactive: sodium or calcium?
A. Sodium
B. Calcium
C. Both equally
D. Cannot be compared
Answer: A
Explanation: Alkali metals are more reactive than alkaline earth metals.
39. Flame test colour of sodium is
A. red
B. green
C. yellow
D. violet
Answer: C
Explanation: Sodium gives characteristic golden yellow flame.
40. Which element gives brick red flame?
A. Sodium
B. Calcium
C. Potassium
D. Barium
Answer: B
Explanation: Calcium salts impart brick red colour.
Section L: Conceptual NCERT-Based MCQs
41. s-Block elements are strong reducing agents because they
A. gain electrons easily
B. lose electrons easily
C. have high electronegativity
D. have stable configuration
Answer: B
Explanation: Easy loss of valence electrons makes them reducing agents.
42. Lithium resembles magnesium due to
A. diagonal relationship
B. same group
C. same atomic mass
D. same size
Answer: A
Explanation: Diagonal relationship explains similarities.
43. Alkali metals form colourless compounds because
A. they have d-electrons
B. they lack d-electrons
C. they have f-electrons
D. they absorb light
Answer: B
Explanation: Absence of d–d transitions gives colourless compounds.
Section M: High-Order Thinking MCQs
44. Which carbonate is thermally unstable?
A. Na₂CO₃
B. K₂CO₃
C. CaCO₃
D. Li₂CO₃
Answer: D
Explanation: Lithium carbonate decomposes on heating.
45. Which chloride has maximum covalent character?
A. NaCl
B. KCl
C. MgCl₂
D. BeCl₂
Answer: D
Explanation: Small Be²⁺ ion polarises chloride ion strongly.
46. Alkaline earth metals do not show variable oxidation states because
A. they have filled d-orbitals
B. they lose only two electrons
C. they are inert
D. they form covalent bonds
Answer: B
Explanation: Only ns² electrons are available for bonding.
47. Which hydroxide is strongest base?
A. Mg(OH)₂
B. Ca(OH)₂
C. Sr(OH)₂
D. Ba(OH)₂
Answer: D
Explanation: Basicity increases down the group.
48. Alkali metals are never found free in nature because they
A. are radioactive
B. are highly reactive
C. are insoluble
D. have low density
Answer: B
Explanation: High reactivity prevents free existence.
49. Which s-block element forms nitride directly with nitrogen?
A. Sodium
B. Potassium
C. Lithium
D. Calcium
Answer: C
Explanation: Lithium uniquely forms Li₃N.
50. The most characteristic property of s-block elements is
A. high electronegativity
B. high ionisation enthalpy
C. metallic and electropositive nature
D. formation of coloured compounds
Answer: C
Explanation: Strong metallic and electropositive character defines s-block elements.
✅ Completion Note
This completes a fully NCERT-aligned, CBSE-standard set of 50 MCQs on s-Block Elements (Alkali and Alkaline Earth Metals), ideal for concept clarity, structured revision, and board exam preparation.