521.

Which of the following has the maximum number of unpaired 'd' electrons?

• Zn²⁺

• Fe²⁺

• Ni³⁺

• Cu⁺

An element with atomic number 21 is a

• halogen

• representative element

• transition element

• alkali metal

Mercury is a liquid metal because

• it has a completely filled s orbital

• it has a small atomic size

• it has a completely filled d orbital that prevents d-d overlapping of orbitals

• it has a completely filled d orbital that causes d-d overlapping

In chromite ore, the oxidation number of iron, and chromium are respectively

• +3,+2

• +3,+6

• +2,+6

• +2,+3

In chromite ore, the oxidation number of iron and chromium are respectively

• +3, +2

• +3, +6

• +2, +6

• +2, +3

The spin only magnetic moment of Mn⁴⁺ ion is nearly

• 3BM

• 6BM

• 4BM

• 5BM

In a transition series, with increase in atomic-number, the paramagnetism

• increases gradually

• decreases gradually

• first increases to a maximum and then decreases

• first decreases to a minimum and then increases

Which of the following is a negatively charged bidentate ligand?

• Cyano

• Ethylene diamine

• Acetato

• Dimethyl glyoximato

The electronic configuration of Cu²⁺ ion is

• [Ar] 3d⁸ 4s¹

• [Ar] 3d⁹ 4s⁰

• [Ar] 3d⁷ 4s²

• [Ar] 3d⁸ 4s⁰

Which one of the following shows highest magnetic moment?

• Fe²⁺

• Co²⁺

• Cr³⁺

• Ni²⁺