p-Block Elements · JEE Main previous year questions

2020 17 questions

1. Q612020 · 6 Sept 2020 · Shift 1

   The correct statement with respect to dinitrogen is :

   1. A.${\mathrm{N}}_2$ is paramagnetic in nature
   2. B.it can be used as an inert diluent for reactive chemicals
   3. C.it can combine with dioxygen at $25^{\circ }\mathrm{C}$
   4. D.liquid dinitrogen is not used in cryosurgery
   Show answer

   Answer: B

2. Q552020 · 6 Sept 2020 · Shift 2

   The average molar mass of chlorine is $35.5\mathrm{g}\mathrm{mo}{\mathrm{l}}^{-1}$. The ratio of ${}^{35}\mathrm{Cl}$ to ${}^{37}\mathrm{Cl}$ in naturally occuring chlorine is close to :

   1. A.$1:1$
   2. B.$2:1$
   3. C.$3:1$
   4. D.$4:1$
   Show answer

   Answer: C

3. Q532020 · 3 Sept 2020 · Shift 1
   
   1. A.(a), (c) and (d)
   2. B.(b) and (c)
   3. C.(c) and (d)
   4. D.(a) and (d)
   Show answer

   Answer: C

4. Q702020 · 3 Sept 2020 · Shift 1

   In a molecule of pyrophosphoric acid, the number of P - OH, P = O and P - O - P bonds/moiety(ies) respectively are :

   1. A.4, 2 and 0
   2. B.4, 2 and 1
   3. C.3, 3 and 3
   4. D.2, 4 and 1
   Show answer

   Answer: B

5. Q722020 · 3 Sept 2020 · Shift 2· Numerical answer

   The volume (in mL) of 0.1 N NaOH required to neutralise 10 mL of 0.1 N phosphinic acid is ___________.

   Show answer

   Answer: 10

6. Q512020 · 2 Sept 2020 · Shift 1
   
   1. A.
   2. B.
   3. C.
   4. D.
   Show answer

   Answer: C

7. Q682020 · 2 Sept 2020 · Shift 1

   The statement that is not true about ozone is :

   1. A.In the stratosphere, CFCs release chlorine free radicals $(\mathrm{Cl})$ which reacts with ${\mathrm{O}}_3$ to give chlorine dioxide radicals
   2. B.It is a toxic gas and its reaction with $\mathrm{NO}$ gives $\mathrm{N}{\mathrm{O}}_2$.
   3. C.In the atmosphere, it is depleted by CFCs
   4. D.In the stratosphere, it forms a protective shield against UV radiation
   Show answer

   Answer: A

8. Q642020 · 2 Sept 2020 · Shift 2

   The shape / structure of $[\mathrm{Xe}{\mathrm{F}}_5{]}^{-}$ and $\mathrm{Xe}{\mathrm{O}}_3{\mathrm{F}}_2$, respectively, are

   1. A.Pentagonal planar and trigonal bipyramidal
   2. B.Trigonal bipyramidal and pentagonal planar
   3. C.Octahedral and square pyramidal
   4. D.Trigonal bipyramidal and trigonal bipyramidal
   Show answer

   Answer: A

9. Q692020 · 2 Sept 2020 · Shift 2

   Two elements A and B have similar chemical properties. They don’t form solid hydrogencarbonates, but react with nitrogen to form nitrides. A and B, respectively, are :

   1. A.Li and Mg
   2. B.Cs and Ba
   3. C.Na and Rb
   4. D.Na and Ca
   Show answer

   Answer: A

10. Q702020 · 2 Sept 2020 · Shift 2

    Amongst the following statements regarding adsorption, those that are valid are (a) $\Delta \mathrm{H}$ becomes less negative as adsorption proceeds (b) On a given adsorbent, ammonia is adsorbed more than nitrogen gas (c) On adsorption, the residual force acting along the surface of the adsorbent increases (d) With increase in temperature, the equilibrium concentration of adsorbate increases

    1. A.(c) and (d)
    2. B.(a) and (b)
    3. C.(d) and (a)
    4. D.(b) and (c)
    Show answer

    Answer: B

11. Q562020 · 9 Jan 2020 · Shift 1

    If the magnetic moment of a dioxygen species is 1.73 B.M, it may be :

    1. A.${\mathrm{O}}_2^{-}$ or ${\mathrm{O}}_2^{+}$
    2. B.${\mathrm{O}}_2$, ${\mathrm{O}}_2^{-}$ or ${\mathrm{O}}_2^{+}$
    3. C.${\mathrm{O}}_2$ or ${\mathrm{O}}_2^{+}$
    4. D.${\mathrm{O}}_2$ or ${\mathrm{O}}_2^{-}$
    Show answer

    Answer: A

12. Q662020 · 8 Jan 2020 · Shift 1
    
    1. A.B > D > A > C
    2. B.D > B > C > A
    3. C.B > A > D > C
    4. D.B > D > C > A
    Show answer

    Answer: B

13. Q702020 · 8 Jan 2020 · Shift 1

    The number of bonds between sulphur and oxygen atoms in ${\mathrm{S}}_2{\mathrm{O}}_8^{2-}$ and the number of bonds between sulphur and sulphur atoms in rhombic sulphur, respectively, are :

    1. A.4 and 8
    2. B.8 and 6
    3. C.4 and 6
    4. D.8 and 8
    Show answer

    Answer: D

14. Q552020 · 8 Jan 2020 · Shift 2

    Kjeldahl's method cannot be used to estimate nitrogen for which of the following compounds?

    1. A.${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{N}{\mathrm{H}}_2$
    2. B.$\mathrm{N}{\mathrm{H}}_2-\mathrm{CON}{\mathrm{H}}_2$
    3. C.${\mathrm{C}}_6{\mathrm{H}}_5\mathrm{N}{\mathrm{O}}_2$
    4. D.$\mathrm{C}{\mathrm{H}}_3\mathrm{C}{\mathrm{H}}_2-\mathrm{C}\equiv \mathrm{N}$
    Show answer

    Answer: C

15. Q572020 · 8 Jan 2020 · Shift 2

    A metal (A) on heating in nitrogen gas gives compound B. B on treatment with ${\mathrm{H}}_2\mathrm{O}$ gives a colourless gas which when passed through $\mathrm{CuS}{\mathrm{O}}_4$ solution gives a dark blue-violet coloured solution. A and B respectively, are :

    1. A.$\mathrm{Na}$ and $\mathrm{NaN}{\mathrm{O}}_3$
    2. B.$\mathrm{Na}$ and $\mathrm{N}{\mathrm{a}}_3\mathrm{N}$
    3. C.$\mathrm{Mg}$ and $\mathrm{M}{\mathrm{g}}_3{\mathrm{N}}_2$
    4. D.$\mathrm{Mg}$ and $\mathrm{Mg}(\mathrm{N}{\mathrm{O}}_3{)}_2$
    Show answer

    Answer: C

16. Q682020 · 8 Jan 2020 · Shift 2

    White Phosphorus on reaction with concentrated $\mathrm{NaOH}$ solution in an inert atmosphere of $\mathrm{C}{\mathrm{O}}_2$ gives phosphine and compound (X). (X) on acidification with $\mathrm{HCl}$ gives compound (Y). The basicity of compound (Y) is :

    1. A.2
    2. B.4
    3. C.1
    4. D.3
    Show answer

    Answer: C

17. Q592020 · 7 Jan 2020 · Shift 1

    The electron gain enthalpy (in kJ/mol) of fluorine, chlorine, bromine and iodine, respectively are:

    1. A.-296, -325, -333 and -349
    2. B.-349, -333, -325 and -296
    3. C.-333, -349, -325 and -296
    4. D.-333, -325, -349 and -296
    Show answer

    Answer: C