On account of the disruption in education due to the corona pandemic, we're opening up our platform for teachers, free of cost. Know More →

JEE Main

Explore popular questions from Some pBlock Elements for JEE Main. This collection covers Some pBlock Elements previous year JEE Main questions hand picked by experienced teachers.

Select Subject

Physics

Chemistry

Mathematics

Some pBlock Elements

Correct Marks 4

Incorrectly Marks -1

Q 1. In {tex} \mathrm { XeF } _ { 2 } , \mathrm { XeF } _ { 4 } , \mathrm { XeF } _ { 6 } {/tex} the number of lone pairs on {tex} \mathrm { Xe } {/tex} are respectively

A

{tex} 2,\ 3, \ 1 {/tex}

B

{tex} 1,\ 2, \ 3 {/tex}

C

{tex} 4, \ 1, \ 2 {/tex}

{tex} 3, \ 2, \ 1 {/tex}.

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 2. Which of the following statements is true?

A

{tex}\mathrm{HF}{/tex} is less polar than {tex}\mathrm{HBr}{/tex}

B

Absolutely pure water does not contain any ions

Chemical bond formation takes place when forces of attraction overcome the forces of repulsion

D

In covalency transference of electron takes place.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 3. When {tex} \mathrm { H } _ { 2 } \mathrm { S } {/tex} is passed through {tex} \mathrm { Hg } _ { 2 } \mathrm { S } {/tex} we get

A

{tex} \mathrm { HgS } {/tex}

B

{tex} \mathrm { HgS } + \mathrm { Hg } _ { 2 } \mathrm { S } {/tex}

{tex} \mathrm { Hg } _ { 2 } \mathrm { S } + \mathrm { Hg } {/tex}

D

{tex} \mathrm { Hg } _ { 2 } \mathrm { S } {/tex}.

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 4. Glass is a

A

micro-crystalline solid

super-cooled liquid

C

gel

D

polymeric mixture.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 5. Graphite is a soft solid lubricant extremely difficult is to melt. The reason for this anomalous behaviour is that graphite

A

is a non-crystalline substance

B

is an allotropic form of diamond

C

has molecules of variable molecular masses like polymers

has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 6. Which one of the following processes doesn't produce hard water?

A

Saturation of water with {tex} \mathrm { CaCO } _ { 3 } {/tex}

B

Saturation of water with {tex} \mathrm { MgCO } _ { 3 } {/tex}

Addition of {tex} \mathrm { Na } _ { 2 } \mathrm { SO } _ { 4 } {/tex} to water

D

Saturation of water with {tex} \mathrm { CaSO } _ { 4 } {/tex}

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 7. Which one of the following substances has the highest proton affinity?

A

{tex} \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} \mathrm { H } _ { 2 } \mathrm { S } {/tex}

{tex} \mathrm { NH } _ { 3 } {/tex}

D

{tex} \mathrm { PH } _ { 3 } {/tex}.

Explanation



As ammonia is strongest base among given compounds, so it has highest affinity for hydrogen ions.

Correct Marks 4

Incorrectly Marks -1

Q 8. Which one of the following is an amphoteric oxide?

{tex} \mathrm { ZnO } {/tex}

B

{tex} \mathrm { Na } _ { 2 } \mathrm { O } {/tex}

C

{tex} \mathrm { SO } _ { 2 } {/tex}

D

{tex}\mathrm B _ { 2 }\mathrm O _ { 3 } {/tex}.

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 9. Concentrated hydrochloric acid when kept in open air sometimes produces a cloud of white fumes. The reason for that could be:

A

concentrated hydrochloric acid emits strongly smelling {tex}\mathrm{HCl}{/tex} gas all the time

B

oxygen in air reacts with the emitted {tex}\mathrm{HCl}{/tex} gas to form a cloud of chlorine gas

strong affinity of {tex}\mathrm{HCl}{/tex} gas for moisture in air results in forming of droplets of liquid solution which appears like a cloudy smoke

D

due to strong affinity for water, concentrated hydrochloric acid pulls moisture of air towards itself. This moisture forms droplets of water and hence the cloud.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 10. The states of hybridisation of boron and oxygen atoms in boric acid {tex} \left( \mathrm { H_3 } \mathrm { BO } _ { 3 } \right) {/tex} are respectively

A

{tex} s p ^ { 2 } {/tex} and {tex} s p ^ { 2 } {/tex}

{tex} s p ^ { 2 } {/tex} and {tex} s p ^ { 3 } {/tex}

C

{tex} s p ^ { 3 } {/tex} and {tex} s p ^ { 2 } {/tex}

D

{tex} s p ^ { 3 } {/tex} and {tex} s p ^ { 3 } {/tex}.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 11. Which one of the following statements regarding helium is incorrect?

It is used to fill gas in balloons instead of hydrogen because it is lighter and non-inflammable.

B

It is used as a cryogenic agent for carrying out experiments at low temperatures.

C

It is used to produce and sustain powerful superconducting magnets.

D

It is used in gas-cooled nuclear reactors.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 12. The molecular shapes of {tex} \mathrm { SF } _ { \mathrm { 4 } } , \mathrm { CF } _ { 4 } {/tex} and {tex} \mathrm { XeF } _ { 4 } {/tex} are

A

the same with {tex} 2,0 {/tex} and {tex}\mathrm{1}{/tex} lone pairs of electrons on the central atom respectively.

B

the same with {tex} 1,1 {/tex} and {tex}\mathrm{1}{/tex} lone pair of electrons on the central atoms respectively.

C

different with {tex} 0,1 {/tex} and {tex}\mathrm{2}{/tex} lone pairs of electrons on the central atom respectively.

different with {tex} 1,0 {/tex} and {tex} 2 {/tex} lone pairs of electrons on the central atom respectively.

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 13. The correct order of the thermal stability of hydrogen halides H-X {tex} ( \mathrm { H } - X ) {/tex} is

A

{tex} \mathrm { HI } > \mathrm { HBr } > \mathrm { HCl } > \mathrm { HF } {/tex}

{tex} \mathrm { HF } > \mathrm { HCl } > \mathrm { HBr } > \mathrm { HI } {/tex}

C

{tex} \mathrm { HCl } < \mathrm { HF } > \mathrm { HBr } < \mathrm { HI } {/tex}

D

{tex} \mathrm { HI } > \mathrm { HCl } < \mathrm { HF } > \mathrm { HBr } {/tex}

Explanation

As the size of the halogen atom increases from F to I, H – X bond length in HX molecules also increases from H – F to H – I (H – F < H – Cl < H – Br < H – I). The increase in H – X bond length decreases the strength of H – X bond from H – F to H – I (H – F > H – Cl > H – Br > H – I). The decrease in the strength of H – X bond is evident from the fact that H – X bond dissociation energies decrease from H – F to H – I. Due to successive decrease in the strength of H – X bond from H – F to H – I, thermal stability of HX molecules also decreases from HF to HI (HF > HCl > HBr > HI).

Correct Marks 4

Incorrectly Marks -1

Q 14. In silicon dioxide

each silicon atom is surrounded by four oxygen atoms and each oxygen atom is bonded to two silicon atoms

B

each silicon atom is surrounded by two oxygen atoms and each oxygen atom is bonded to two silicon atoms

C

silicon atom is bonded to two oxygen atoms

D

there are double bonds between silicon and oxygen atoms

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 15. Which of the following statements is true?

A

{tex} \mathrm { H } _ { 3 } \mathrm { PO } _ { 3 } {/tex} is a stronger acid than {tex} \mathrm { H } _ { 2 } \mathrm { SO } _ { 3 } {/tex}

B

In aqueous medium {tex}\mathrm{HF}{/tex} is a stronger acid than {tex} \mathrm { HCl } {/tex}

C

{tex} \mathrm { HClO } _ { 4 } {/tex} is a weaker acid than {tex}\mathrm{HClO}_3{/tex}

{tex} \mathrm { HNO } _ { 3 } {/tex} is a stronger acid than {tex} \mathrm { HNO } _ { 2 } {/tex}.

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 16. The stability of dihalides of {tex}\mathrm{Si}{/tex}, {tex}\mathrm{Ge}{/tex}, {tex}\mathrm{Sn}{/tex} and {tex}\mathrm{Pb}{/tex} increases steadily in the sequence

A

{tex} \mathrm { Pb } X _ { 2 } < \mathrm { Sn } X _ { 2 } <\mathrm { Ge } X _ { 2 } < \mathrm { Si } X _ { 2 } {/tex}

B

{tex} \mathrm { Ge } X _ { 2 } < \mathrm { Si } X _ { 2 } < \mathrm { Sn } X _ { 2 } < \mathrm { Pb } X _ { 2 } {/tex}

{tex} \mathrm { Si } X _ { 2 } < \mathrm { Ge } X _ { 2 }< \mathrm { Pb } X _ { 2 } < \mathrm { Sn } X _ { 2 } {/tex}

D

{tex} \mathrm { Si } X _ { 2 } < \mathrm { Ge } X _ { 2 } < \mathrm { Sn } X _ { 2 } < \mathrm { Pb } X _ { 2 } {/tex}.

Explanation



The stability of dihalides increases down the group:

Correct Marks 4

Incorrectly Marks -1

Q 17. Identify the incorrect statement among the following.

A

{tex}\mathrm {Br}_2{/tex} reacts with hot and strong {tex} \mathrm {NaOH} {/tex} solution to give {tex} \mathrm {NaBr} {/tex} and {tex} \mathrm { H } _ { 2 } \mathrm { O } {/tex}.

B

Ozone reacts with {tex} \mathrm { SO } _ { 2 } {/tex} to give {tex} \mathrm { SO } _ { 3 } {/tex}.

C

Silicon reacts with {tex} \mathrm { NaOH } _ { ( a q ) } {/tex} in the presence of air to give {tex} \mathrm { Na } _ { 2 } \mathrm { SiO } _ { 3 } {/tex} and {tex} \mathrm { H } _ { 2 } \mathrm { O } {/tex}.

{tex} \mathrm { Cl } _ { 2 } {/tex} reacts with excess of {tex} \mathrm { NH } _ { 3 } {/tex} to give {tex} \mathrm { N } _ { 2 } {/tex} and {tex} \mathrm { HCl } {/tex}.

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 18. In context with the industrial preparation of hydrogen from water gas {tex} \left( \mathrm { CO } + \mathrm { H } _ { 2 } \right) , {/tex} which of the following is the correct statement?

{tex} \mathrm { CO} {/tex} is oxidised to {tex} \mathrm { CO } _ { 2 } {/tex} with steam in the presence of a catalyst followed by absorption of {tex} \mathrm { CO } _ { 2 } {/tex} in alkali

B

{tex}\mathrm { CO}{/tex} and {tex} \mathrm { H } _ { 2 } {/tex} are fractionally separated using differences in their densities

C

{tex}\mathrm{CO}{/tex} is removed by absorption in aqueous {tex} \mathrm { Cu } _ { 2 } \mathrm { Cl } _ { 2 } {/tex} solution

D

{tex} \mathrm { H } _ { 2 } {/tex} is removed through occlusion with {tex} \mathrm { Pd } {/tex}

Explanation


Correct Marks 4

Incorrectly Marks -1

Q 19. Among the following substituted silanes the one which will give rise to cross linked silicone polymer on hydrolysis is

A

{tex} \mathrm { R } _ { 3 } \mathrm { SiCl } {/tex}

B

{tex}\mathrm R _ { 4 }\mathrm S \mathrm i {/tex}

{tex} \mathrm { RSiCl } _ { 3 } {/tex}

D

{tex} \mathrm { R } _ { 2 } \mathrm { SiCl } _ { 2 } {/tex}

Explanation