281.

The order of covalent character of KF, KI, KCl is

• KCl < KF < KI

• KI < KCl < KF

• KF < KI < KCl

• KF < KCl < Kl

Which one of the following forms a basic oxide?

• B

• Tl

• Al

• Ga

The gas produced by the passage of air over hot coke is

• carbon monoxide

• carbon dioxide

• producer gas

• water gas

Inorganic graphite is

• B₂H₆

• BN

• BF₃

• B₂N₃H₆

The bonding in diborane (B₂H₆) can be described by

• 4 two centre - two electron bonds and 2 three - centre- two electron bonds

• 3 two centre - two electron bonds and 3 three - centre- two electron bonds

• 2 two centre - two electron bonds and 4 three centre - two electron bonds

• 4 two centre - two electron bonds and 4 two- centre- two electron bonds

Which of the following elements lowest melting point?

• Sn

• Pb

• Si

• Ge

The amorphous form of silica is:

• Tridymite

• Quartz

• Kieselguhr

• Cristobalite

The correct statements among I to III regarding group 13 element oxides are,

(I) Boron trioxide is acidic.

(II) Oxides of aluminium and gallium are amphoteric.

(III) Oxides of indium and thallium are basic.

• (I) and (II) only

• (I), (II) and (III)

• (I) and (III) only

• (II) and (III) only

C₆₀ an allotrope of carbon contains:

• 18 hexagons and 14 pentagons

• 20 hexagons and 12 pentagons

• 12 hexagons and 20 pentagons

• 16 hexagons and 16 pentagons

The correct order of catenation is

• Si >Sn >C >Ge

• C >Sn> Si ≈Ge

• Ge >Sn >Si >C

• C> Si> Ge ≈C