Diborane is used for reduction of :

• carboxylic acids

• esters

• nitro groups

• Both (a) and (b)

Which material is used as a neutron moderator?

• Graphite

• Cadmium

• Boron

• Uranium

Assertion : Conductivity of silicon increases by doping it with group-15 elements.

Reason : Doping means introduction of small amount of impurities like P, As or Bi into the pure crystal.

• 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.

Which of the following shows bond in silicone?

• Si-C-Si-C-Si

• Si-Si-Si-Si

• -Si-O-Si-O-Si-

• Si-C-Si-O-Si

Which of the following is an example of chain silicates?

• Kaolinite

• Zircon

• Benitonite

• Diopside

Crystalline form of silica is called :

• crystalline silicon

• quartz

• rock

• talc

157.

The elements commonly used for making transistors are :

• Ga and In

• C and Si

• P and As

• Si and Ge

Which of the following products are formed when SiCl₄ vapour are passed over hot Mg ?

• SiCl₂ + MgCl₂

• Si + MgCl₂

• Mg₂Si + MgCl₂

• MgSiCl₆

Which of the following gas is linear ?

• CO₂

• SO₂

• NO₂

• SO₃

The repeating unit in silicone is

• SiO₂

• R₂Si-O^-

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