21.

An organic compound having molecular mass 60 is found to contain C = 20%, H = 6.67% and N = 46.67% while rest is oxygen. On heating, it gives NH3 along with a solid residue. The solid residue give violet colour with alkaline copper sulphate solution. The compound is

• CH₃NCO

• CH₃CONH₂

• (NH₂)₂CO

• (NH₂)₂CO

Which of the following oxides is amphoteric in character?

• CaO

• CO₂

• SiO₂

• SiO₂

If α is the degree of dissociation of Na₂SO₄, the vant Hoff’s factor (i) used for calculating the molecular mass is

• 1 + α

• 1 - α

• 1 +2α

• 1 +2α

The oxidation state of Cr in [Cr(NH₃)₄Cl₂]⁺ is

• +3

• +1

• 0

• 0

Hydrogen bomb is based on the principle of

• Nuclear fission

• Natural radioactivity

• Nuclear fusion

• Nuclear fusion

An ionic compound has a unit cell consisting of A ions at the corners of a cube and B ions on the centres of the faces of the cube. The empirical formula for this compound would be

• A₂B

• AB

• AB₃

• AB₃

Lattice energy of an ionic compounds depends upon

• Charge on the ion only

• Size of the ion only

• Packing of ions only

• Packing of ions only

The highest electrical conductivity of the following aqueous solutions is of

• 0.1 M acetic acid

• 0.1 M chloroacetic acid

• 0.1 M fluoroacetic acid

• 0.1 M fluoroacetic acid

Aluminium oxide may be electrolysed at 1000^o  C to furnish aluminium metal (Atomic mass = 27 amu; 1 Faraday = 96,500 Coulombs). The cathode reaction is

Al³⁺ +3e^- → Al^o
To prepare 5.12 kg of aluminium metal by this method would require

• 5.49 x 10⁷ C of electricity

• 1.83 x 10⁷ C of electricity

• 1.49x 10⁷ C of electricity

• 1.49x 10⁷ C of electricity

Consider an endothermic reaction, X → Y with the activation energies E_b and E_f for the backward and forward reactions, respectively. In general

• E_b < E_f

• E_b > E_fEb > Ef

• E_b = E_f

• E_b = E_f