S-Block Elements NEET PYQs (2005–2026) with Solutions

10 solved S-Block Elements PYQs

Real NEET and AIPMT questions from this chapter, newest first. Try each one, then open the answer and the step-by-step explanation.

1. Question 1 (NEET 2026)

   NEET 2026MediumReaction of CO₂ with carbon (Boudouard reaction)

   When 1 dm³ of CO₂ gas is passed over hot coke, the volume of gaseous mixture after complete reaction at STP becomes 1.4 dm³. The composition of the gaseous mixture at STP is:

   1. AOption A: 0.8 dm³ of CO, 0.8 dm³ of CO₂
   2. BOption B: 0.8 dm³ of CO, 0.6 dm³ of CO₂
   3. COption C: 0.6 dm³ of CO, 0.8 dm³ of CO₂
   4. DOption D: 0.6 dm³ of CO, 0.4 dm³ of CO₂

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   Correct answer: (B) 0.8 dm³ of CO, 0.6 dm³ of CO₂

   Explanation

   Reaction: CO₂ + C → 2CO. Let x dm³ CO₂ react. Final volume=(1−x)+2x=1+x=1.4 ⇒ x=0.4. Therefore remaining CO₂=0.6 dm³ and CO formed=0.8 dm³. Hence option (B) is correct.

2. Question 2 (NEET 2024)

   NEET 2024MediumQualitative Analysis of Cations

   Given below are certain cations. Using inorganic qualitative analysis, arrange them in increasing group number from 0 to VI. A. Al³⁺ B. Cu²⁺ C. Ba²⁺ D. Co²⁺ E. Mg²⁺ Choose the options from the given below:

   1. AOption A: E, C, D, B, A
   2. BOption B: E, A, B, C, D
   3. COption C: B, A, D, C, E
   4. DOption D: B, C, A, D, E

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   Correct answer: (C) B, A, D, C, E

   Explanation

   Classification in qualitative analysis: Cu²⁺ → Group II Al³⁺ → Group III Co²⁺ → Group IV Ba²⁺ → Group V Mg²⁺ → Group VI Thus increasing order of group number is: $$B, A, D, C, E$$ Hence, option (C) is correct.

3. Question 3 (NEET 2022)

   NEET 2022MediumProperties of Alkali Metals

   Identify the incorrect statement from the following:

   1. AOption A: Lithium is the strongest reducing agent among the alkali metals
   2. BOption B: Alkali metals react with water to form their hydroxides
   3. COption C: The oxidation number of K in KO₂ is +4
   4. DOption D: Ionisation enthalpy of alkali metals decreases from top to bottom in the group

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   Correct answer: (C) The oxidation number of K in KO₂ is +4

   Explanation

   In KO₂ (potassium superoxide), oxidation state of K is +1 and O₂⁻ has charge −1. Therefore oxidation number of K is not +4. Hence option (C) is incorrect.

4. Question 4 (NEET 2021)

   NEET 2021EasyAlkaline Earth Metals

   Among the following alkaline earth metal halides, one which is covalent and soluble in organic solvents is:

   1. AOption A: Beryllium chloride
   2. BOption B: Calcium chloride
   3. COption C: Strontium chloride
   4. DOption D: Magnesium chloride

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   Correct answer: (A) Beryllium chloride

   Explanation

   Due to the small size and high polarising power of Be²⁺, BeCl₂ shows covalent character and is soluble in organic solvents.

5. Question 5 (NEET 2020)

   NEET 2020EasyBiological Importance of Alkali Metals

   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.

   1. AOption A: Iron
   2. BOption B: Copper
   3. COption C: Calcium
   4. DOption D: Potassium

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   Correct answer: (D) Potassium

   Explanation

   Potassium ions activate several enzymes, help in ATP production during glucose oxidation and, along with sodium ions, are responsible for nerve impulse transmission. Hence, option (D) is correct.

6. Question 6 (NEET 2019)

   NEET 2019EasyHydration of Alkali Metal Chlorides

   Which of the alkali metal chloride $(\mathrm{MCl})$ forms its dihydrate salt $(\mathrm{MCl \cdot 2H_2O})$ easily?

   1. AOption A: $\mathrm{KCl}$
   2. BOption B: $\mathrm{LiCl}$
   3. COption C: $\mathrm{CsCl}$
   4. DOption D: $\mathrm{RbCl}$

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   Correct answer: (B) $\mathrm{LiCl}$

   Explanation

   Among alkali metal chlorides, only lithium chloride readily forms hydrated salts due to the small size and high polarising power of the $\mathrm{Li^+}$ ion. Therefore, lithium chloride forms the dihydrate: $$\mathrm{LiCl \cdot 2H_2O}$$ Other alkali metal chlorides generally do not form hydrates easily. Hence, the correct option is (2).

7. Question 7 (NEET 2017)

   NEET 2017MediumHydration Energy and Ionic Mobility

   Ionic mobility of which of the following alkali metal ions is lowest when aqueous solution of their salts are put under an electric field?

   1. AOption A: Li
   2. BOption B: Na
   3. COption C: K
   4. DOption D: Rb

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   Correct answer: (A) Li

   Explanation

   Li⁺ has the highest charge density and is most strongly hydrated among alkali metal ions. Due to large hydrated size, Li⁺ shows the lowest ionic mobility in aqueous solution.

8. Question 8 (NEET 2016)

   NEET 2016EasyCalcium Compounds

   The suspension of slaked lime in water is known as:

   1. AOption A: Limewater
   2. BOption B: Quicklime
   3. COption C: Milk of lime
   4. DOption D: Aqueous solution of slaked lime

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   Correct answer: (C) Milk of lime

   Explanation

   A suspension of slaked lime $Ca(OH)_2$ in water is called milk of lime. Hence option (C) is correct.

9. Question 9 (NEET 2016)

   NEET 2016MediumAnomalous Behaviour of Beryllium

   In context with beryllium, which one of the following statements is incorrect?

   1. AOption A: It is rendered passive by nitric acid
   2. BOption B: It forms $Be_2C$
   3. COption C: Its salts rarely hydrolyze
   4. DOption D: Its hydride is electron-deficient and polymeric

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   Correct answer: (C) Its salts rarely hydrolyze

   Explanation

   Beryllium salts hydrolyze readily because of the small size and high polarizing power of $Be^{2+}$ ion. Therefore the statement 'Its salts rarely hydrolyze' is incorrect. Hence option (C) is correct.

10. Question 10 (AIPMT 2015)

    AIPMT 2015EasyThermal Stability of Carbonates

    On heating which of the following releases $\mathrm{CO_2}$ most easily?

    1. AOption A: $\mathrm{MgCO_3}$
    2. BOption B: $\mathrm{CaCO_3}$
    3. COption C: $\mathrm{K_2CO_3}$
    4. DOption D: $\mathrm{Na_2CO_3}$

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    Correct answer: (A) $\mathrm{MgCO_3}$

    Explanation

    The ease of decomposition of carbonates depends on their thermal stability. The thermal stability order is: $$\mathrm{K_2CO_3 > Na_2CO_3 > CaCO_3 > MgCO_3}$$ Since $\mathrm{MgCO_3}$is the least thermally stable among the given carbonates, it decomposes most readily on heating:$$\mathrm{MgCO_3 \xrightarrow{\Delta} MgO + CO_2}$$ Hence, option (A) is correct.