Among the following, which is water insoluble?

• Sodium fluoride

• Potassium fluoride

• Beryllium fluoride

• Magnesium fluoride

Solvay process is used in the manufacture of

• K₂CO₃

• KHCO₃

• Na₂CO₃

• CaCl₂

Assertion (A) -  K, Rb and Cs form superoxides.

Reason (R) - The stability of the superoxides increases from K to Cs due to decrease in lattice energy.

The correct answer is

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

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

• (A) is true but (R) is not true.

• (A) is not true but (R) is true.

In photoelectric effect, if the energy required to overcome the attractive forces on the electron, (work functions) of Li, Na and Rb are 2.41 eV, 2.30 eV and 2.09 eV respectively, the work function of 'K could approximately be in eV.

• 2.52

• 2.20

• 2.35

• 2.01

Na₂S₂O₃ reacts with moist Cl₂ to form Na₂SO₄, HCl and X. Which one of the following is X?

• H₂S

• SO₂

• SO₃

• S

Ni anode is used in the electrolytic extraction of

• Al

• Mg

• Na by Down's process

• Na by Castner's process

Which of the following is not correct?

• LiOH is a weaker base than NaOH.

• Salts of Be undergo hydrolysis

• Ca(HCO₃)₂ is soluble in water.

• Hydrolysis of beryllium carbide gives acetylene.

Which one of the following elements reduces NaOH to Na?

• Si

• Pb

• C

• Sn

69.

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