Hydrogen & s-Block · JEE Main previous year questions

2021 13 questions

1. Q722021 · 1 Sept 2021 · Shift 2

   The potassium ferrocyanide solution gives a Prussian blue colour, when added to :

   1. A.$\mathrm{CoC}{\mathrm{l}}_3$
   2. B.$\mathrm{FeC}{\mathrm{l}}_2$
   3. C.$\mathrm{CoC}{\mathrm{l}}_2$
   4. D.$\mathrm{FeC}{\mathrm{l}}_3$
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   Answer: D

2. Q792021 · 1 Sept 2021 · Shift 2

   Hydrogen peroxide reacts with iodine in basic medium to give :

   1. A.$\mathrm{I}{\mathrm{O}}_4^{-}$
   2. B.$\mathrm{I}{\mathrm{O}}^{-}$
   3. C.${\mathrm{I}}^{-}$
   4. D.$\mathrm{I}{\mathrm{O}}_3^{-}$
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   Answer: C

3. Q842021 · 1 Sept 2021 · Shift 2· Numerical answer

   The number of atoms in $8\mathrm{g}$ of sodium is $x\times 10^{23}$. The value of x is ____. (Nearest integer) [Given : ${\mathrm{N}}_{\mathrm{A}}=6.02\times 10^{23}\mathrm{mo}{\mathrm{l}}^{-1}$ Atomic mass of $\mathrm{Na}=23.0\mathrm{u}$]

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   Answer: 2

4. Q612021 · 26 Aug 2021 · Shift 2
   
   1. A.
   2. B.
   3. C.
   4. D.
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   Answer: B

5. Q722021 · 27 Jul 2021 · Shift 2

   Which one of the following sets of elements can be detected using sodium fusion extract?

   1. A.Sulfur, Nitrogen, Phosphorus, Halogens
   2. B.Phosphorus, Oxygen, Nitrogen, Halogens
   3. C.Nitrogen, Phosphorus, Carbon, Sulfur
   4. D.Halogens, Nitrogen, Oxygen, Sulfur
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   Answer: A

6. Q782021 · 25 Jul 2021 · Shift 1

   Given below are two statements : Statement I : None of the alkaline earth metal hydroxides dissolve in alkali. Statement II : Solubility of alkaline earth metal hydroxides in water increases down the group. In the light of the above statements, choose the most appropriate answer from the options given below :

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

7. Q832021 · 25 Jul 2021 · Shift 1· Numerical answer

   A source of monochromatic radiation of wavelength 400 nm provides 1000 J of energy in 10 seconds. When this radiation falls on the surface of sodium, $x\times 10^{20}$ electrons are ejected per second. Assume that wavelength 400 nm is sufficient for ejection of electron from the surface of sodium metal. The value of x is ____. (Nearest integer) (h = $6.626\times 10^{-34}$ Js)

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   Answer: 2

8. Q702021 · 25 Jul 2021 · Shift 2

   Which one of the following metals forms interstitial hydride easily?

   1. A.Cr
   2. B.Fe
   3. C.Mn
   4. D.Co
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   Answer: A

9. Q712021 · 25 Jul 2021 · Shift 2

   [structure: Maleic anhydride (five-membered cyclic anhydride with C=C)] Maleic anhydride can prepared by :

   1. A.Heating trans-but-2-enedioic acid
   2. B.Heating cis-but-2-enedioic acid
   3. C.Treating cis-but-2-enedioic acid with alcohol and acid
   4. D.Treating trans-but-2-enedioic acid with alcohol and acid
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   Answer: B

10. Q772021 · 22 Jul 2021 · Shift 2

    When silver nitrate solution is added to potassium iodide solution then the sol produced is :

    1. A.$AgI/{\mathrm{I}}^{-}$
    2. B.$AgI/A{\mathrm{g}}^{+}$
    3. C.$KI/N{\mathrm{O}}_3^{-}$
    4. D.$\mathrm{AgN}{\mathrm{O}}_3/N{\mathrm{O}}_3^{-}$
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    Answer: A

11. Q772021 · 18 Mar 2021 · Shift 1

    Match List - I with List - II $$\begin{array}{llll}& \text{List - I}& & \text{List - II}\\ \text{(a)}& \mathrm{Ca}(\mathrm{OCl}{)}_2& \text{(i)}& \text{Antacid}\\ \text{(b)}& \mathrm{CaS}{\mathrm{O}}_4\cdot \frac{1}{2}{\mathrm{H}}_2\mathrm{O}& \text{(ii)}& \text{Cement}\\ \text{(c)}& \mathrm{CaO}& \text{(iii)}& \text{Bleach}\\ \text{(d)}& \mathrm{CaC}{\mathrm{O}}_3& \text{(iv)}& \text{Plaster of paris}\end{array}$$ Choose the most appropriate answer from the options given below :

    1. A.(a) - (i), (b) - (iv), (c) - (iii), (d) - (ii)
    2. B.(a) - (iii), (b) - (ii), (c) - (iv), (d) - (i)
    3. C.(a) - (iii), (b) - (iv), (c) - (ii), (d) - (i)
    4. D.(a) - (iii), (b) - (ii), (c) - (i), (d) - (iv)
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    Answer: C

12. Q772021 · 26 Feb 2021 · Shift 2

    Match List - I with List - II. | List - I | List - II | | :--- | :--- | | (a) Sodium Carbonate | (i) Deacon | | (b) Titanium | (ii) Castner-Kellner | | (c) Chlorine | (iii) van-Arkel | | (d) Sodium hydroxide | (iv) Solvay | Choose the correct answer from the options given below :

    1. A.(a) $\to$ (iv), (b) $\to$ (iii), (c) $\to$ (i), (d) $\to$ (ii)
    2. B.(a) $\to$ (iv), (b) $\to$ (i), (c) $\to$ (ii), (d) $\to$ (iii)
    3. C.(a) $\to$ (iii), (b) $\to$ (ii), (c) $\to$ (i), (d) $\to$ (iv)
    4. D.(a) $\to$ (i), (b) $\to$ (iii), (c) $\to$ (iv), (d) $\to$ (ii)
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    Answer: A

13. Q722021 · 25 Feb 2021 · Shift 2

    Which of the following compound is added to the sodium extract before addition of silver nitrate for testing of halogens?

    1. A.Nitric acid
    2. B.Sodium hydroxide
    3. C.Ammonia
    4. D.Hydrochloric acid
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    Answer: A