71.

On reduction of KMnO₄, by oxalic acid in acidic medium, the oxidation number of Mn changes. What is the magnitude of this change?

• From 7 to 2

• From 6 to 2

• From 5 to 2

• From 7 to 4

Zinc and mercury do not show variable valency like d-block elements because

• they are soft

• their d- shells are complete

• they have only two electron in the outer most sub shell

• Their d- shell are completed

Which of the following sulphate is insoluble in water?

• CuSO₄

• CdSO₄

• PbSO₄

• Bi₂(SO₄)₃

A deep brown gas is formed by mixing two colourless gases which are

• NO₂ and O₂

• N₂O and NO

• NO and O₂

• NH₃ and HCl

In the nitrogen family the H-M-H bond angle in the hydrides (MH₃ ) gradually becomes closer to 90° on going from N to Sb. This shows that

• the basic strength of hydrides increases

• the bond energies of M-H bonds increases

• almost pure p-orbitals are used for M-H bonding

• the bond pairs of electrons come nearer to the central atom

Mark the oxide which is amphoteric in character

• CO₂

• SiO₂

• SnO₂

• CaO

The pair of coordination compounds [Co(NH₃)₅Br]SO₄ and [Co(NH₃)₅SO₄]Br is an example for

• geometrical isomerism

• coordination isomerism

• structural isomerism

• ionisation isomerism

The correct nomenclature Fe₄[Fe(CN)₆]₃

• ferroso ferric cyanide

• ferric- ferrous hexacyanate

• iron(III) hexacyanoferrate(II)

• hexa cyanoferrate(III-II)

Which one of the following will give a white precipitate with AgNO₃ in aqueous medium?

• [Co(NH₃)₂Cl] (NO₂)₂

• [Pt(NH₃)₂Cl₂]

• [Pt(en) Cl₂]

• [Pt(NH₃)₄]Cl₂

Which one of the following sulphide is yellow?

• Zinc sulphide

• Cadmium sulphide

• Nickel sulphide

• Lead sulphide