The vapour pressure of two liquids P and Q are 80 and 60 torr, respectively. The total vapour pressure of solution obtained by mixing 3 moles of P and 2 moles of Q would be

• 140 torr

• 20 torr

• 68 torr

• 72 torr

The energy of second Bohr orbit of the hydrogen atom is -328 kJ mol^-1; hence the energy of fourth Bohr orbit would be

• -41 kJ mol^-1

• -1312 kJ mol^-1

• -164 kJ mol^-1

• -82 kJ mol^-1

Which one of the following arrangements represents the correct order of electron gain enthalpy (with negative sign) of the given atomic species ?

• Cl < F < S < O

• O < S < F < Cl

• S < O < Cl < F

• F < Cl < O < S

What amount of bromine will be required to convert 2 g of phenol into 2, 4, 6-bribromo phenol?

• 20.44 gm

• 6.00 gm

• 4.00 gm

• 10.22 gm

The concentration of H₂O₂ solution of 10 volume is

• 30%

• 3%

• 1%

• 10%

26.

The dipole moment of HBr is 1.6 × 10^-30 cm and inter-atomic spacing is 1 Å. The % ionic character of HBr is

• 7

• 10

• 15

• 27

Graphite is a soft solid lubricant extremely difficult to melt. The reason for this anomalous behaviour is that, graphite

• is a non-crystalline substance

• is an allotropic form of diamond

• has molecules of variable molecular masses like polymers

• has carbon atoms arranged in large plates of rings of strongly bound carbon atoms with weak interplate bonds

Alkyl halides react with dialkyl copper reagents to give

• alkenyl halides

• alkanes

• alkyl copper halides

• alkenes

The structure of diborane (B₂H₆) contains

• four 2C-2e^- bonds and four 3C-2e^- bonds

• two 2C-2e^- bonds and two 3C-3e^- bonds

• two 2C-2e^- bonds and four 3C-2e^- bonds

• four 2C-2e^- bonds and two 3C-2e^- bonds

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 alongwith a solid residue. The solid residue give violet colour with alkaline copper sulphate solution. The compound is

• CH₃CH₂CONH₂

• (NH₂)₂CO

• CH₃CONH₂

• CH₃NCO