NEET Previous Year Questions (2014-2024): The s-Block Elements (Old NCERT) | Chemistry Class 11 PDF Download

Q.1. Given below are two statements: one is labelled as Assertion A and the other is labelled as Reason R:    (2023)
Assertion A: Metallic sodium dissolves in liquid ammonia giving a deep blue solution, which is paramagnetic.
Reason R: The deep blue solution is due to the formation of amide.
In the light of the above statements, choose the correct answer from the options given below:
A: Both A and R are true and R is the correct explanation of A
B: Both A and R are true but R is NOT the correct explanation of A
C: A is true but R is false
D: A is false but R is true
Ans: C
On dissolving alkali metal (sodium) in liquid ammonia, a deep blue solution is developed due to ammoniated electron which absorbs energy in visible region of light and imparts blue colour. Due to unpaired electron, solution is paramagnetic.

So, assertion statement is correct but reason is incorrect.

Q.2. Which one of the following statements is correct?    (2023)
A: The daily requirement of Mg and Ca in the human body is estimated to be 0.2-0.3 g
B: All enzymes that utilise ATP in phosphate transfer require Ca as the cofactor
C: The bone in human body is an inert and unchanging substance
D: Mg plays roles in neuromuscular function and interneuronal transmission
Ans: A

• All enzymes that utilize ATP in phosphate transfer require Mg as the co-factor.
• Bone in human body is not an inert and unchanging substance but is continuously being solubilised and redeposited. 
• Ca plays important role in neuromuscular function, interneuronal transmission, cell membrane integrity and blood coagulation.
• The daily requirement of Mg and Ca in the human body is estimated to be 200 - 300 mg (0.2 - 0.3 g).

Q.3. Match List - I with List - II.
Choose the correct answer from the options given below:    (2022)
(a) (a)-(i), (b)-(iii), (c)- (iv), (d)-(ii)
(b) (a)-(ii), (b)- (iii), (c)- (i), (d)- (iv)
(c) (a)-(iv), (b)-(i), (c)-(iii), (d)-(ii)
(d) (a)-(iii), (b)- (iv), (c)- (ii), (d)-(i)
Ans: B
KOH → Absorbs CO₂ 
Li → Used in Electrochemical cells  
Na → Coolant in fast breeder reactors
Cs → Used in photoelectric cells

Q.4. Among the following alkaline earth metal halides, one which is covalent and soluble in organic solvents is:      (2021)
(a) Magnesium chloride
(b) Beryllium chloride
(c) Calcium chloride
(d) Strontium chloride
Ans: b

BeCl2 is covalent and soluble in a organic solvent.

Q.5. The structures of beryllium chloride in solid state and vapour phase, are :      (2021)
(a) Dimer and Linear, respectively.
(b) Chain in both.
(c) Chain and dimer, respectively.
(d) Linear in both.
Ans: c

The structures of beryllium chloride in the solid state and vapour phase, respectively are chain and dimeric.
In vapour phase at above 900^∘C. BeCl₂ is monomeric having a linear structure Cl−Be−Cl. The bonding in BeCl₂ is covalent and Be atom accommodates 2 + 2 = 4 electrons in the two sp− hybrid orbitals. Below 900^∘C, beryllium chloride in vapour phase exists as a mixture of monomer BeCl₂ and Be₂Cl₄.

Q.6. The following metal ion activates many enzymes, participates in the oxidation of glucose to produce ATP and with Na, is responsible for the transmission of nerve signals.     (2021)
(a) Calcium
(b) Potassium
(c) Iron
(d) Copper
Ans: b

Q.7. Which of the following is an amphoteric hydroxide?    (2019)
(a) Sr(OH)₂
(b) Ca(OH)₂
(c) Mg(OH)₂
(d) Be(OH)₂
Ans: d
Be(OH)₂ is amphoteric in nature, since it can react with both acid and base
Be(OH)₂ + 2HCl → BeCl₂ + 2H₂O
Be(OH)₂ + 2NaOH → Na₂ [Be(OH)₄]

Q.8. Enzymes that utilize ATP in phosphate transfer require an alkaline earth metal (M) as the co-factor. M is :    (2019)
(a) Be
(b) Mg
(c) Ca
(d) Sr
Ans: b
All enzymes that utilize ATP in phosphate transfer require magnesium(Mg) as the co-factor.

Q.9. Which of the following oxides is most acidic in nature?    (2018)
(a) MgO
(b) BeO
(c) BaO
(d) CaO
Ans: b
In metals moving down the group metallic character increases, So basic nature increases down the group. Hence, most acidic will be BeO.

Q.10. Among CaH₂, BeH₂, BaH₂, the order of ionic character is    (2018)
(a) BeH₂ < CaH₂ < BaH₂
(b) CaH₂ < BeH₂ < BaH₂
(c) BeH₂ < BaH₂ < CaH₂
(d) BaH₂ < BeH₂ < CaH₂
Ans: a
BeH₂ < CaH₂ < BaH₂
Smaller the size of cation, more will be its polarising power. Hence BeH₂ will be least ionic.

Q.11. Ionic mobility of which of the following alkali metalions is lowest when aqueous solution of their saltsare put under an electric field ?    (2017)
(a) K
(b) Rb
(c) Li
(d) Na
Ans: c


Q.12. Which of the following statement is false ?    (2016)
(a) Mg²⁺ ions are important in the green parts of plants.
(b) Mg²⁺ ions from a complex with ATP.
(c) Ca²⁺ ions are important in blood clotting.
(d) Ca²⁺ ions are not important in maintaining the regular beating of the heart.
Ans: d
Ca⁺² ions are important in blood clotting and are also important in maintaining the regular beating of the heart.

Q.13. The function of 'sodium pump' is a biological process operating in each and every cell of all animal. Which of the following biologically important ions is also a constituent of this pump?    (2015)
(a) Fe²⁺
(b) Ca²⁺
(c) Mg²⁺
(d) K⁺
Ans: d
The sodium pump is also known as a sodium Potassium pump. This pump is important contributor to action potential produced by nerve cells. The process of moving sodium potassium ions across the cell membranes is active transport process involving the hydrolysis of ATP to provide the necessary energy.

Q.14. Solubility of the alkaline earth‘s metal sulphates in water decreases in the sequence :    (2015)
(a) Ba > Mg > Sr > Ca
(b) Mg > Ca > Sr > Ba
(c) Ca > Sr > Ba > Mg
(d) Sr > Ca > Mg > Ba
Ans: b
Mg > Ca > Sr > Ba.
The solubility of sulphates decreases on moving down the group. The values of solubility products which decrease gradually also explain the decrease in solubility on moving down the group.