The correct order of radii is

• N <Be <B

• F^-<O^2-<N^3-

• Na< Li< K

• Fe³⁺< Fe²⁺< Fe⁴⁺

Which of the following element shows maximum valency ?

• Carbon

• Barium

• Nitrogen

• Sulphur

123.

The metal used to recover copper from a solution of CuSO₄ is :

• Fe

• He

• Na

• Ag

Which of the following elements never show positive oxidation number?

• O

• Fe

• Ga

• F

Which of the following element is a metalloid?

• Bi

• Sn

• Ge

• C

What is the name of element with atomic number 105?

• Kurchatovium

• Dubnium

• Nobelium

• Holmium

Which among the following elements have lowest value of IE₁?

• Pb

• Sn

• Si

• C

KI and CusO₄ solution when mixed, give :

• CuI₂ + K₂SO₄

• Cu₂I₂ + K₂SO₄

• K₂SO₄ + Cu₂I₂ + I₂

• K₂SO₄ + CuI₂ + I₂