221.

Metals are good conductor of electricity because they contain :

• a network structure

• ionic bonds

• very few valence electrons

• free electrons

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

Among the following components of cement which is present in highest amount?

• Ca₂SiO₄

• Ca₃SiO₅

• Al₂O₃

• Ca₃Al₂O₆

Radioactive metal is :

• Li

• Ce

• Na

• Ra

The pair whose both species are used in antiacid medicinal preparation is

• NaHCO₃ and Mg(OH)₂

• Na₂CO₃ and Ca(HCO₃)₂

• Ca(HCO₃)₂ and Mg(OH)₂

• Ca(OH)₂ and NaHCO₃.

Which of the following is a false statement ?

• Fluorine is more electronegative than chlorine

• Nitrogen has greater IE₁ than oxygen

• Lithium is amphoteric

• Chlorine is an oxidising agent

Which of the following is a use of alum ?

• Making explosives

• Bleaching clothes

• Water softening

• All of the above

The pair of amphoteric hydroxides is

• Al(OH)₃, LiOH

• Be(OH)₂, Mg(OH)₂

• B(OH)₃, Be(OH)₂

• Be(OH)₂, Zn(OH)₂

Which of the following is only acidic nature?

• Be(OH)₂

• Mg(OH)₂

• B(OH)₃

• Al(OH)₃