51.

In which of the following the inert pair effect is most prominent?

• C

• Si

• Ge

• Pb

The metal that does not give the borax bead test is

• Chromium

• nickel

• lead

• manganese

Which one of the following is a good conductor of electricity?

• Diamond

• Graphite

• Silicon

• Amorphous carbon

Which one of the following is maximum electronegative?

• lead

• Silicon

• Carbon

• Tin

Buckminster-fullerene is a variety of

• boron

• carbon

• ammonia

• fluorine

Doping of silicon with boron leads to

• n-type semiconductor

• p-type semiconductor

• superconductor

• insulator

The substance not likely to contain CaCO₃ is

• marble statue

• calcined gypsum

• sea shells

• dolomite

The electronic configuration of an element C is 1s², 2s², 2p⁶. The formula of substance containing only C will be

• C₈

• C₄

• C₂

• C

Number of carbon atoms in kerosene is

• C_17-20

• C_12-16

• C_20-25

• C_25-30

C¹⁴ is

• a natural non-radioactive isotope

• an artificial non-radioactive isotope

• an artificial radioactive isotope

• a natural radioactive isotope