21.

The gas evolved on heating alkali formate with soda-lime is

• CO

• CO₂

• hydrogen

• water vapour

Which of the following is known as dead burnt?

• Gypsum

• Plaster of Paris

• Anhydrite

• None of these

Thomas slag is

• Ca₃(PO₄)₂.2H₂O

• Ca₃(PO₄)₂.CaSiO₃

• MgSiO₃

• CaSiO₃

The hydrolysis of sodium carbonate involves the reaction between

• sodium ion and water

• Na⁺ and OH^-

• ${\mathrm{CO}}_3^{2-} \mathrm{and} \mathrm{water}$

• ${\mathrm{CO}}_3^{2-} \mathrm{and} {\mathrm{H}}^{+}$

Potassium metabisulphite is a(an)

• preservative

• antioxidant

• artificial sweetener

• Both (a) and (b)

When Zn is treated with excess of NaOH, the product obtained is

• Zn(OH)₂

• ZnOH

• Na₂ZnO₂

• None of the above

The reaction of sodium acetate and sodalime gives

• butane

• ethane

• methane

• propane

Gypsum is

• CaSO₄·H₂O

• CaSO₄·2H₂O

• 2CaSO₄·2H₂O

• CaSO₄

Solubility of which among the following substances in water increases slightly with rise in temperature?

• Potassium bromide

• Potassium chloride

• Potassium nitrate

• Sodium nitrate

When potassium is reacted with water which compound(s) is are formed preferentially?

• K₂O

• KO₂

• Both K₂O and KO₂

• K₂O₂