An f-shell containing 6 unpaired electrons can exchange

• 6 electrons

• 9 electrons

• 12 electrons

• 15 electrons

Among the elements Ca, Mg, P and Cl, the order of increasing atomic radii is

• Mg< Ca< Cl< P

• Cl <P <Mg< Ca

• P <Cl< Ca< Mg

• Ca <Mg <P < Cl

Among the following which one has the highest cation of anion size ratio?

• Csl

• CsF

• LiF

• NaF

What is the value of electron gain enthalpy of Na if IE₁ of Na = 5.1 eV?

• -5.1 eV

• -10.2 eV

• +2.55 eV

• +10.2eV

Assertion (A): K, Rb and Cs form superoxides.

Reason (R): The stability of the superoxides increases from 'K' to 'Cs' due to decrease in lattice energy.

The correct answer is

• Both (A) and (R) are true and (R) is the correct explanation of (A).

• Both (A) and (R) are true but (R) is not the correct explanation of (A)

• (A) is true but (R) is not true

• (A) is not true but (R) is true

Which one of the following order is correct for the first ionisation energies of the elements?

• B <Be <N < O

• Be <B <N < O

• B <Be <O <N

• B <O <Be <N

The oxidation number of oxygen in KO₃, Na₂O₂ is

• 3, 2

• 1, 0

• 0, 1

• -0.33, -1

What is the fuel of atomic pile ?

• Thorium

• Sodium

• Uranium

• Petroleum

39.

The maximum number of unpaired electrons is present in

• Fe

• Cu

• Co

• Ni

The pair, that is referred as 'chemical twins' is

• Ac, Cf

• Hf, Ta

• Tc, Re

• La, Ac