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 sBlock Element (Alkali and Alkaline earth metals) for JEE Main. This collection covers sBlock Element (Alkali and Alkaline earth metals) previous year JEE Main questions hand picked by experienced teachers.

Select Subject

Physics

Chemistry

Mathematics

sBlock Element (Alkali and Alkaline earth metals)

Correct Marks 4

Incorrectly Marks -1

Q 1. {tex} \mathrm { KO } _ { 2 } {/tex} (potassium super oxide) is used in oxygen cylinders in space and submarines because it

absorbs {tex} \mathrm { CO } _ { 2 } {/tex} and increases {tex} \mathrm { O } _ { 2 } {/tex} content

B

eliminates moisture

C

absorbs {tex} \mathrm { CO } _ { 2 } {/tex}

D

produces ozone.

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 2. A metal M readily forms its sulphate {tex}\mathrm{ MSO}_4 {/tex}, which is water- soluble. It forms its oxide {tex}\mathrm{MO}{/tex} which becomes inert on heating. It forms an insoluble hyroxide {tex}\mathrm{M(OH)} _ { 2 } {/tex} which is soluble in {tex}\mathrm{NaOH}{/tex} solution. Then {tex} \mathrm { M } {/tex} is

A

{tex} \mathrm { Mg } {/tex}

B

{tex} \mathrm { B a } {/tex}

C

{tex} \mathrm { Ca } {/tex}

{tex} \mathrm { Be } {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 3. In curing cement plasters water is sprinkled from time to time. This helps in

developing interlocking needle-like crystals of hydrated silicates

B

hydrating sand and gravel mixed with cement

C

converting sand into silicic acid

D

keeping it cool

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 4. The substance not likely to contain {tex} \mathrm { CaCO } _ { 3 } {/tex} is

calcined gypsum

B

sea shells

C

dolomite

D

a marble statue

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 5. Which one of the following processes will produce hard water?

A

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

Saturation of water with {tex} \mathrm {CaSO_4}{/tex}

C

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

D

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

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 6. Which of the following species is diamagnetic in nature?

A

{tex} \mathrm { H } _ { 2 } ^ { - } {/tex}

B

{tex} \mathrm { H } _ { 2 } ^ { + } {/tex}

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

D

{tex} \mathrm { He } _ { 2 } ^ { + } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 7. The ionic mobility of alkali metal ions in aqueous solution is maximum for

A

{tex} \mathrm { Li } ^ { + } {/tex}

B

{tex} \mathrm { Na } ^ { + } {/tex}

C

{tex} K ^ { + } {/tex}

{tex} \mathrm { Rb } ^ { + } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 8. Very pure hydrogen {tex} ( 99.9 ) {/tex} can be made by which of the following processes?

A

Reaction of methane with steam

B

Mixing natural hydrocarbons of high molecular weight

C

Electrolysis of water

Reaction of salts like hydrides with water

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 9. The molecular formula of a commercial resin used for exchanging ions in water softening is {tex} \mathrm { C } _ { 8 } \mathrm { H } _ { 7 } \mathrm { SO } _ { 3 } ^ { - } \mathrm { Na } ^ { + } {/tex} (Mol. wt. {tex} 206 . {/tex} What would be the maximum uptake of {tex} \mathrm { Ca } ^ { 2 } + {/tex} ions by the resin when expressed in mole per gram resin?

A

{tex} \frac { 2 } { 309 } {/tex}

{tex} \frac { 1 } { 412 } {/tex}

C

{tex} \frac { 1 } { 103 } {/tex}

D

{tex} \frac { 1 } { 206 } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 10. Which one of the following statements about water is FALSE?

There is extensive intramolecular hydrogen bonding in the condensed phase.

B

Ice formed by heavy water sinks in normal water.

C

Water is oxidized to oxygen during photosynthesis.

D

Water can act both as an acid and as a base.

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 11. The main oxides formed on combustion of {tex} \mathrm { Li, Na}{/tex} and {tex} \mathrm { K } {/tex} in excess of air are, respectively:

A

{tex} \mathrm { Li } _ { 2 } \mathrm { O } _ { 2 } , \mathrm { Na } _ { 2 } \mathrm { O } _ { 2 } {/tex} and {tex} \mathrm { KO } _ { 2 } {/tex}

{tex} \mathrm { Li } _ { 2 } \mathrm { O } , \mathrm { Na } _ { 2 } \mathrm { O } _ { 2 } {/tex} and {tex} \mathrm { KO } _ { 2 } {/tex}

C

{tex} \mathrm { Li } _ { 2 } \mathrm { O } , \mathrm { Na } _ { 2 } \mathrm { O } {/tex} and {tex} \mathrm { KO } _ { 2 } {/tex}

D

{tex} \mathrm { LiO } _ { 2 } , \mathrm { Na } _ { 2 } \mathrm { O } _ { 2 } {/tex} and {tex} \mathrm { K } _ { 2 } \mathrm { O } {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 12. From the following statements regarding {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } , {/tex} choose the incorrect statement:

A

It has to be stored in plastic or wax lined glass bottles in dark

B

It has to be kept away from dust

It can act only as an oxidizing agent

D

It decomposes on exposure to light

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 13. 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?

A

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

B

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

C

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

{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

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 14. In which of the following reactions {tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } {/tex} acts as a reducing agent?

A

{tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } + 2 \mathrm { H } ^ { + } + 2 \mathrm { e } ^ { - } \rightarrow 2 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

B

{tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } + 2 \mathrm { e } ^ { - } \rightarrow \mathrm { O } _ { 2 } + 2 \mathrm { H } ^ { + } {/tex}

C

{tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } + 2 \mathrm { e } ^ { - } \rightarrow 2 \mathrm { OH } ^ { - } {/tex}

{tex} \mathrm { H } _ { 2 } \mathrm { O } _ { 2 } + 2 \mathrm { OH } ^ { - } - 2 \mathrm { e } ^ { - } \rightarrow \mathrm { O } _ { 2 } + 2 \mathrm { H } _ { 2 } \mathrm { O } {/tex}

Explanation



Correct Marks 4

Incorrectly Marks -1

Q 15. Which of the following atoms has the highest first ionization energy?

A

{tex} \mathrm { K } {/tex}

{tex} \mathrm { S } { \mathrm { c } } {/tex}

C

{tex} \mathrm { Rb } {/tex}

D

{tex} \mathrm { Na } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 16. The correct increasing order of densities of alkali metals is

A

{tex} \mathrm { Li } < \mathrm { Na } < \mathrm { K } < \mathrm { Rb } < \mathrm { Cs } {/tex}

B

{tex} \mathrm { Cs } < \mathrm { Rb } < \mathrm { K } < \mathrm { Na } < \mathrm { Li } {/tex}

{tex} \mathrm { Li } < \mathrm { K } < \mathrm { Na } < \mathrm { Rb } < \mathrm { Cs } {/tex}

D

{tex} \mathrm { K } < \mathrm { Na } < \mathrm { Li } < \mathrm { Rb } < \mathrm { Cs } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 17. Which one of the following alkali metals is the most metallic?

A

{tex}\mathrm{ L i }{/tex}

B

{tex} \mathrm { Na } {/tex}

C

{tex}\mathrm{ K} {/tex}

{tex} \mathrm { Cs } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 18. The metallic lusture exhibited by sodium is due to

A

Diffusion of {tex} \mathrm { Na } ^ { + } {/tex} ions

Oscillation of loose electrons

C

Excitation of free protons

D

Existence of body centred cubic lattice

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 19. Which among the following is the strongest reducing agent?

{tex}\mathrm K {/tex}

B

{tex} \mathrm { Na } {/tex}

C

{tex} \mathrm {Al} {/tex}

D

{tex} \mathrm { Mg } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 20. Sodium chloride gives a golden yellow colour to the bunsen flame, which is due to

A

Sublimation of metallic sodium to give yellow vapour

B

Photosensitivity of sodium

C

Low ionization potential of sodium

Emission of excess of energy absorbed as a radiation in the visible region

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 21. In the manufacture of sodium hydroxide, by product obtained is

A

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

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

C

{tex} \mathrm { Na } _ { 2 } \mathrm { CO } _ { 3 } {/tex}

D

{tex} \mathrm { NaCl } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 22. Which of the following alkali metal bicarbonates readily decomposes?

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

B

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

C

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

D

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

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 23. Which of the following halides has the highest melting point?

A

{tex} \mathrm { NaCl } {/tex}

B

{tex} \mathrm { NaBr } {/tex}

{tex} \mathrm {NaF}{/tex}

D

{tex} \mathrm { NaI } {/tex}

Explanation

Correct Marks 4

Incorrectly Marks -1

Q 24. Which of the following alkaline earth metal does not impart any colour to flame?

A

{tex} \mathrm { Be } {/tex}

{tex} \mathrm { Mg } {/tex}

C

{tex} \mathrm { Ca } {/tex}

D

{tex} \mathrm { Sr } {/tex}

Correct Marks 4

Incorrectly Marks -1

Q 25. Lime water is an aqueous solution of

A

{tex} \mathrm { MgSO } _ { 4 } {/tex}

{tex} \mathrm { Ca } ( \mathrm { OH } ) _ { 2 } {/tex}

C

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

D

{tex} \mathrm { CaSO } _ { 4 } {/tex}

Explanation