Hydrogen & s-Block · JEE Main previous year questions

2023 29 questions

1. Q682023 · 25 Jan 2023 · Shift 1

   '25 volume' hydrogen peroxide means

   1. A.1 L marketed solution contains 75 g of ${\mathrm{H}}_2{\mathrm{O}}_2$.
   2. B.1 L marketed solution contains 250 g of ${\mathrm{H}}_2{\mathrm{O}}_2$.
   3. C.1 L marketed solution contains 25 g of ${\mathrm{H}}_2{\mathrm{O}}_2$.
   4. D.100 mL marketed solution contains 25 g of ${\mathrm{H}}_2{\mathrm{O}}_2$.
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   Answer: A

2. Q792023 · 25 Jan 2023 · Shift 1

   Compound A reacts with $\mathrm{N}{\mathrm{H}}_4\mathrm{Cl}$ and forms a compound B. Compound B reacts with ${\mathrm{H}}_2\mathrm{O}$ and excess of $\mathrm{C}{\mathrm{O}}_2$ to form compound C which on passing through or reaction with saturated NaCl solution forms sodium hydrogen carbonate. Compound A, B and C, are respectively :

   1. A.$\mathrm{Ca}(\mathrm{OH}{)}_2,\mathrm{N}{\mathrm{H}}_4^{\oplus },(\mathrm{N}{\mathrm{H}}_4{)}_2\mathrm{C}{\mathrm{O}}_3$
   2. B.$\mathrm{CaC}{\mathrm{l}}_2,\mathrm{N}{\mathrm{H}}_4^{\oplus },(\mathrm{N}{\mathrm{H}}_4{)}_2\mathrm{C}{\mathrm{O}}_3$
   3. C.$\mathrm{CaC}{\mathrm{l}}_2,\mathrm{N}{\mathrm{H}}_3,\mathrm{N}{\mathrm{H}}_4\mathrm{HC}{\mathrm{O}}_3$
   4. D.$\mathrm{Ca}(\mathrm{OH}{)}_2,\mathrm{N}{\mathrm{H}}_3,\mathrm{N}{\mathrm{H}}_4\mathrm{HC}{\mathrm{O}}_3$
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   Answer: D

3. Q772023 · 24 Jan 2023 · Shift 2

   Given below are two statements, one is labelled as Assertion A and the other is labelled as Reason R Assertion A : Beryllium has less negative value of reduction potential compared to the other alkaline earth metals. Reason R : Beryllium has large hydration energy due to small size of $\mathrm{B}{\mathrm{e}}^{2+}$ but relatively large value of atomization enthalpy In the light of the above statements, choose the most appropriate answer from the options given below :

   1. A.Both A and R are correct but R is NOT the correct explanation of A
   2. B.Both A and R are correct and R is the correct explanation of A
   3. C.A is correct but R is not correct
   4. D.A is not correct but R is correct
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   Answer: B

4. Q792023 · 24 Jan 2023 · Shift 2

   Identify the correct statements about alkali metals. A. The order of standard reduction potential $({\mathrm{M}}^{+}\mid \mathrm{M})$ for alkali metal ions is $\mathrm{Na}>\mathrm{Rb}>\mathrm{Li}$. B. CsI is highly soluble in water. C. Lithium carbonate is highly stable to heat. D. Potassium dissolved in concentrated liquid ammonia is blue in colour and paramagnetic. E. All the alkali metal hydrides are ionic solids. Choose the correct answer from the options given below :

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