21.

Which of the following species is not electrophilic in nature?

• $\stackrel{\oplus }{\mathrm{C}}\mathrm{l}$

• BH₃

• ${\mathrm{H}}_3\stackrel{\oplus }{\mathrm{O}}$

• $\stackrel{\oplus }{\mathrm{N}}{\mathrm{O}}_2$

Match List I with List II for the compositions of substances and select the correct answer using the codes given below the lists.

• A   B   C   D

  3   4   1   2

• A   B   C   D

  2   3   4    1

• A   B   C   D

  1   2   3    5

• A   B   C   D

  4   3   2    1

Mg is an important component of which biomolecule occurring extensively in living world?

• Haemoglobin

• Chlorophyll

• Florigen

• ATP

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