The pair of amphoteric hydroxides is

• Al(OH)₃, LiOH

• Be(OH)₂, Mg(OH)₂

• B(OH)₃, Be(OH)₂

• Be(OH)₂, Zn(OH)₂

Which of the following is only acidic nature?

• Be(OH)₂

• Mg(OH)₂

• B(OH)₃

• Al(OH)₃

The molecular formula of 'salt petre' is :

• KNO₃

• NaNO₃

• NaCl

• Na₂SO₄

On dissolving moderate amount of sodium metal in liquid NH₃ at low temperature, which one of the following does not occur?

• Blue coloured solution is obtained.

• Na⁺ ions are formed in the solution.

• Liquid NH₃ becomes good conductor of electricity

• Liquid ammonia remains diamagnetic

Which of the following reaction produces hydrogen ?

• Mg + H₂O

• H₂S₂O₈ + H₂O

• BaO₂ + HCl

• Na₂O₂ + 2HCl

Assertion: Mg is not present in enamel of human teeth.

Reason : Mg is an essential element for biological functions of human.

• If both assertion and reason are true and reason is the correct explanation of assertion

• If both assertion and reason are true but reason is not the correct explanation of assertion

• If assertion is true but reason is false

• If both assertion and reason are false.

Match the flame colours of the alkaline earth metal salts in the Bunsen burner.

• A - p; B - r; C - q

• A - r; B - p; C - q

• A - q; B - r; C - p

• A - p; B - q; C - r

Which of the following has highest hydration energy?

• MgCl₂

• CaCl₂

• BaCl₂

• SrCl₂

Addition of sodium thiosulphate solution to a solution of silver nitrate gives X as white precipitate, insoluble in water but soluble in excess thiosulphate solution to give Y. On boiling in water, Y gives Z. X, Y and Z respectively are

• Ag₂S₂O₃, Na₃[Ag(S₂O₃)₂], Ag₂S

• Ag₂SO₄, Na[Ag(S₂O₃)₂], Ag₂S₂

• Ag₂S₂O₃, Na₅[Ag(S₂O₃)₃], AgS

• Ag₂SO₃, Na₃[Ag(S₂O₃)₂], Ag₂O

70.

The aqueous solution of which of the following salt will have the lowest pH ?

• NaClO₃

• NaClO

• NaClO₄

• NaClO₂