Which one of the following elements reduces NaOH to Na?

• Si

• Pb

• C

• Sn

Assertion (A) : Alkali metals are soft and have low melting and boiling points.

Reason (R) : This is because interatomic bonds are weak.

• Both (A) and (R) are not true.

• (A) is true but (R) is not the correct explanation of (A).

• (A) is true but (R) is false.

• Both (A) and (R) are true and (R) is the correct explanation of (A).

Consider the following statements-

I. Cs⁺ ion is more highly hydrated than other alkali metal ions.

II. Among the alkali metals, only lithium forms a stable, nitride by direct combination with nitrogen.

III. Among the alkali metals Li, Na, K, Rb the metal, Rb has the highest melting point.

IV. Among the alkali metals Li, Na, K, Rb only Li forms peroxide when heated with oxygen.

Select the correct statement is

• I

• II

• III

• IV

284.

Which of the following reactions does not involve liberation of oxygen?

• XeF₄ + H₂O → 

• XeF₄ + O₂F₂ → 

• XeF₂ + H₂O → 

• XeF₆ + H₂O → 

Which one of the following statements is not correct?

• The hydration enthalpies of alkali metal ions decrease down the group.

• LIthium halides are some what covalent in nature

• Alkali metals react with water liberating oxygen gas

• KO₂ is paramagnetic.

The formula of phosphate of a metal, M is MPO₄. The formula of its nitrate will be

• M NO₃

• M (NO₃)₂

• M (NO₃)₃

• M₂(NO₃)₃

The formula of phosphate of a metal, M is M NH₄PO₄. The formula of its sulphate will be

• M SO₄

• M (SO₄)₂

• M₂SO₄

• M₂ (SO₄)₃

With the increase in atomic weights, melting points of the alkali metals

• increase

• decrease

• remain constant

• do not show definite trend

Alkali metals in each period have

• smallest size

• owest ionization potential

• highest ionisation potential

• highest electronegativity

In potassium manganate, the oxidation state of manganese is

• +5

• +6

• +7

• +8