Assertion : s-block elements do not occur free in nature

Reason :  s-block elements are highly electropositive in nature.

1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion
2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion
3. If the assertion is true but the reason is false
4. If both the assertion and reason are false

The cation of alkali metals are found as M(H₂O)⁺_n in H₂O, value of 'n' is maximum for

1. Na⁺

2. K⁺

3. Rb⁺

4. Li⁺

1 mole of substance (X) was treated with an excess of water. 2 moles of readily combustible gas were produced along with solution which when reacted with CO₂ gas produced a white turbidity. The substance (X) could be

(1) Ca

(2) CaH₂

(3) Ca(OH)₂

(4) Ca(NO₃)₂

A chloride dissolves appreciably in cold water. When placed on a Pt-wire in Bunsen flame, no distinctive colour is noticed. Cation present is

(1) Mg²⁺

(2) Ba²⁺

(3) Pb²⁺

(4) Ca²⁺

The fire extinguisher contains NaHCO₃ and the compound (X). The compound (X) maybe -

1. CH₃COOH

2. NaOH

3. C₆H₅OH

4. None of the above. 

Alkali metals do not form nitride on reaction with N₂, whereas lithium forms Li₃N, because

(1) High ionisation energy of Li

(2) High lattice energy of Li₃N

(3) High sublimation energy of Li

(4) High covalent nature of Li₃N

All group-2 metals dissolve in liquid ammonia to produce a bright blue colour. The colour is due to-

1. A change in the structure of ammonia.

2. d-d transition.

3. The spectrum of the solvated electrons.

4. An electronic transition from a lower to a higher energy state.

$∆{\mathrm{H}}_{\mathrm{solution}}$ is positive for

I. LiF

II. CsI

III. RbF

IV. KF

(1) I, II, III & IV

(2) II only

(3) I only

(4) I & II only

While moving down the group (in alkaline earth metals) following property increases except

(1) Radius

(2) Solubility of hydroxides

(3) Solubility of sulphates

(4) Thermal stability of carbonates

A chemical compound A is used for water softening to remove temporary hardness. A reacts with Na₂CO₃ to form caustic soda. When CO₂ is bubbled through A it becomes cloudy. The chemical formula of A is

(1) CaO

(2) Ca(OH)₂

(3) Ca(HCO₃)₂

(4) CaCO₃