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Assertion: K, Rb and Cs form superoxides...

Assertion: K, Rb and Cs form superoxides.
Reason: The stability of the superoxides increases from 'K' to 'Cs'
due to decrease in lattice energy.

A

Both (A) and (R) are true and (R) is the correct explanation of (A)

B

Both (A) and (R) are true and (R) is not the correct explanation of (A)

C

(A) is true but (R) is false

D

(A) is false but (R) is true

Text Solution

Verified by Experts

The correct Answer is:
A
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K, Rb and Cs form mainly superoxides.

The ionisation energy of alkali metals decreases from Li to Cs bacause

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2 ,it will take up further oxygen at elevated pressure and temperature to form NaO_2 .The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. Solution of sodium metals in liquid ammonia is strongly reducing due to the presence of :

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2 ,it will take up further oxygen at elevated pressure and temperature to form NaO_2 .The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. KO_2 is used in oxygen cylinders in space and submarines because it :

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2 ,it will take up further oxygen at elevated pressure and temperature to form NaO_2 .The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. Select the correct choice for alkali metal oxides.

Alkali metals oxide are obtained by combustion of the metals.Although Na normally gives Na_2O_2 ,it will take up further oxygen at elevated pressure and temperature to form NaO_2 .The per and superoxides of the heavier alkalies can also be prepared by passing stoichiometric amounts of oxygen into their solution in liquid ammonia. The different alkali metal oxides can be distinguished by reaction with water.The superoxides reacts with CO_2 and give oxygen gas.The stability of per and superoxides is based upon that larger cation can stablise larger anion, due to larger lattice energy. Alkali metals dissolve in liquid ammonia.Dilute solutions are dark blue in colour but as the concentration increases above 3M, the colour changes to copper bronze and the solution acquires the metallic lusture due to the formation of metal ions clusters.The solutions of alkali metals in liquid ammonia are good conductors of electricity due to the presence of ammoniated cations and ammoniated electrons.However, the conductivity decreases as the concentrations increases, since ammoniated electrons and ammoniated cation associate. On dissolving smaller (less than 3M) amount of sodium metal in liquid ammonia at low temperature , which one of the following does not occur ?

K, Rb and Cs form which type of compounds with oxygen?

Assertion : Generally alkali and alkaline earth metals form superoxides. Reason : There is single bond between O and O in superoxides.

The stability of peroxide and superoxide of alkali metals increase as we go down to group. Explain giving reason.

Assertion : A change in the temperature of a body cause change in dimentions. Reason : The dimentions of a body decrease due to the increase in its temperature.