Hydrogen & s-Block · JEE Main previous year questions

2025 7 questions

1. Q582025 · 4 Apr 2025 · Shift 1
   
   1. A.
   2. B.
   3. C.
   4. D.
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   Answer: C

2. Q682025 · 4 Apr 2025 · Shift 2

   Given below are two statements : Statement (I) : Alcohols are formed when alkyl chlorides are treated with aqueous potassium hydroxide by elimination reaction. Statement (II) : In alcoholic potassium hydroxide, alkyl chlorides form alkenes by abstracting the hydrogen from the $\beta$-carbon. In the light of the above statements, choose the most appropriate answer from the options given below :

   1. A.Both Statement I and Statement II are incorrect
   2. B.Both Statement I and Statement II are correct
   3. C.Statement I is incorrect but Statement II is correct
   4. D.Statement I is correct but Statement II is incorrect
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   Answer: C

3. Q722025 · 4 Apr 2025 · Shift 2· Numerical answer

   The amount of calcium oxide produced on heating $150\mathrm{kg}$ limestone ( $75\%$ pure) is $\underline{}\mathrm{kg}$. (Nearest integer) Given: Molar mass (in ${\mathrm{gmol}}^{-1}$) of Ca-40, O-16, C-12

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   Answer: 63

4. Q542025 · 3 Apr 2025 · Shift 2

   Mass of magnesium required to produce $220\mathrm{mL}$ of hydrogen gas at STP on reaction with excess of dil. $\mathrm{HCl}$ is Given: Molar mass of $\mathrm{Mg}$ is $24{\mathrm{g}\mathrm{mol}}^{-1}$.

   1. A.$0.24\mathrm{mg}$
   2. B.$235.7\mathrm{g}$
   3. C.$2.444\mathrm{g}$
   4. D.$236\mathrm{mg}$
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   Answer: D

5. Q682025 · 3 Apr 2025 · Shift 2

   Compounds that should not be used as primary standards in titrimetric analysis are : A. ${\mathrm{Na}}_2{\mathrm{Cr}}_2{\mathrm{O}}_7$ B. Oxalic acid C. $\mathrm{NaOH}$ D. ${\mathrm{FeSO}}_4\cdot 6{\mathrm{H}}_2\mathrm{O}$ E. Sodium tetraborate Choose the most appropriate answer from the options given below:

   1. A.C, D and E Only
   2. B.B and D Only
   3. C.D and E Only
   4. D.A, C and D Only
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   Answer: D

6. Q652025 · 2 Apr 2025 · Shift 2

   The nature of oxide $(\mathrm{Te}{\mathrm{O}}_2)$ and hydride $(\mathrm{Te}{\mathrm{H}}_2)$ formed by $\mathrm{Te}$, respectively are :

   1. A.Reducing and basic
   2. B.Reducing and acidic
   3. C.Oxidising and acidic
   4. D.Oxidising and basic
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   Answer: C

7. Q562025 · 24 Jan 2025 · Shift 1

   Preparation of potassium permanganate from $\mathrm{Mn}{\mathrm{O}}_2$ involves two step process in which the 1st step is a reaction with $\mathrm{KOH}$ and $\mathrm{KN}{\mathrm{O}}_3$ to produce

   1. A.${\mathrm{K}}_3\mathrm{Mn}{\mathrm{O}}_4$
   2. B.${\mathrm{K}}_4[\mathrm{Mn}(\mathrm{OH}{)}_6]$
   3. C.${\mathrm{K}}_2\mathrm{Mn}{\mathrm{O}}_4$
   4. D.$\mathrm{KMn}{\mathrm{O}}_4$
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   Answer: C