21.

Which of the following is an example of chain silicates?

• Kaolinite

• Zircon

• Benitonite

• Diopside

Which of the following elements shows +4 oxidation state?

• Sn

• Ra

• Fr

• Sc

CH₃(CH₂)₄CH₃ $\underset{773 \mathrm{K}, 10-20 \mathrm{atm}}{\overset{{\mathrm{Cr}}_2{\mathrm{O}}_3/ {\mathrm{Al}}_2{\mathrm{O}}_3}{\to }} \mathrm{A} \stackrel{{\mathrm{Br}}_2/ \mathrm{Fe}}{\to } \mathrm{B} \underset{\mathrm{ether}}{\overset{\mathrm{Mg}}{\to }} \mathrm{C} \stackrel{{\mathrm{H}}_2\mathrm{O}}{\to } \mathrm{D}$

What is D?

The correct order of stability of the superoxides is

• KO₂ > RbO₂ > CsO₂

• KO₂ > CsO₂ > RbO₂

• CsO₂ > RbO₂ > KO₂

• RbO₂ > CsO₂ > KO₂

Which of the following fluorides has the lowest melting point?

• BaF₂

• SrF₂

• CaF₂

• BeF₂

Which of the following has the highest tendency to give the reaction,

M⁺_(g) $\underset{\mathrm{medium}}{\overset{\mathrm{aqueous}}{\to }}$ M⁺_(aq.) ?

• Na

• Li

• K

• Rb

How many geometrical isomers are possible in the following two alkenes ?

(i) CH₃ - CH = CH - CH = CH - CH₃

(ii) CH₃ - CH = CH - CH = CH - Cl

• 4 and 4

• 4 and 3

• 3 and 3

• 3 and 4.

Assertion : Electromeric effect is brought into play only at the requirement of the reagent.

Reason : It is a temporary effect in which bond pair is shifted to one of the constituent atoms.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion: Cis-2-butene gives meso-2, 3-butanediol with dilute alkaline KMnO₄ solution.

Reason : Dilute alkaline KMnO₄ solution gives trans addition with alkenes.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false

Assertion : The presence of Ag⁺ enhances the solubility of alkenes in water.

Reason : Alkenes are weakly polar in nature.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false