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.

235.

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

A. Calcium	p. Brick red
B. Strontium	q. Apple green
C. Barium	r. Crimson

• 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

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

• NaClO₃

• NaClO

• NaClO₄

• NaClO₂

Assertion : Na₂SO₄ is soluble in water while BaSO₄ is not.

Reason : Lattice energy of BaSO₄ exceeds its hydration energy.

• 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 Assertion is false but Reason is true.

Identify the correct order of solubility in aqueous medium.

• CuS > ZnS > Na₂S

• ZnS > Na₂S > CuS

• Na₂S > CuS > ZnS

• Na₂S > ZnS > CuS