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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.

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sBlock Element (Alkali and Alkaline earth metals)

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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

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Q 2. The metallic sodium disolves in liquid ammonia to form a deep blue coloured solution. The deep blue colour is due to formation of:

solvated electron, {tex} \mathrm { e } \left( \mathrm { NH } _ { 3 } \right) _ { \mathrm { x } } ^ { - } {/tex}

B

solvated atomic sodium, {tex} \mathrm { Na } \left( \mathrm { NH } _ { 3 } \right) _ { \mathrm { y } } {/tex}

C

{tex} \left( \mathrm { Na } ^ { + } + \mathrm { Na } ^ { - } \right) {/tex}

D

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

Explanation



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Q 3. 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



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Q 4. 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

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Q 5. The substance not likely to contain {tex} \mathrm { CaCO } _ { 3 } {/tex} is

calcined gypsum

B

sea shells

C

dolomite

D

a marble statue

Explanation

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Q 6. The solubilities of carbonates decrease down the magnesium group due to a decrease in

hydration energies of cations

B

inter-ionic attraction

C

entropy of solution formation

D

lattice energies of solids

Explanation


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Q 7. 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

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Q 8. One mole of magnesium nitride on the reaction with an excess of water gives:

two moles of ammonia

B

one mole of nitric acid

C

one mole of ammonia

D

two moles of nitric acid

Explanation

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Q 9. 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

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Q 10. Which of the following statements in relation to the hydrogen atom is correct?

{tex} 3 s , 3 p {/tex} and {tex} 3d {/tex} orbitals all have the same energy

B

{tex} 3s {/tex} and {tex} 3p {/tex} orbitals are of lower energy than {tex} 3d {/tex} orbital

C

{tex} 3p {/tex} orbital is lower in energy than {tex} 3d {/tex} orbital

D

{tex} 3s {/tex} orbital is lower in energy than {tex} 3p {/tex} orbital

Explanation


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Q 11. 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

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Q 12. Which of the following on thermal decomposition yields a basic as well as acidic oxide?

A

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

B

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

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

D

{tex} \mathrm { NH } _ { 4 } \mathrm { NO } _ { 3 } {/tex}

Explanation

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Q 13. 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

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Q 14. 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

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Q 15. 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

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Q 16. 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