Which of the following is an organometallic compound?

• Lithium methoxide

• Lithium acetate

• Lithium dimethylamide

• Methyl lithium

A compound X on heating gives a colourless gas. The residue is dissolved in water to obtain Y. Excess CO₂ is passed through aqueous solution of Y when Z is formed. Z on gentle heating gives back X. The compound X is

• Ca(HCO₃)₂

• CaCO₃

• NaHCO₃

• Na₂CO₃

With excess of water, both P₂O₅ and PCl₅ give

• H₃PO₃

• H₃PO₂

• H₃PO₄

• H₄P₂O₇

Which sequence of reactions shows correct chemical relation between sodium and its compounds?

• $\mathrm{Na} + {\mathrm{O}}_2 \to {\mathrm{Na}}_2\mathrm{O} \stackrel{\mathrm{HCl}\left(\mathrm{aq}\right)}{\to }\mathrm{NaCl}\stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{∆}{\to }\mathrm{Na}$

• $\mathrm{Na}\stackrel{{\mathrm{O}}_2}{\to }{\mathrm{Na}}_2\mathrm{O}\stackrel{{\mathrm{H}}_2\mathrm{O}}{\to }\mathrm{NaOH}\stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{∆}{\to }\mathrm{Na}$

• $\mathrm{Na}+{\mathrm{H}}_2\mathrm{O} \to \mathrm{NaOH}\stackrel{\mathrm{HCl}}{\to }\mathrm{NaCl}\stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_2\stackrel{∆}{\to }\mathrm{Na}$

• $\mathrm{Na}+{\mathrm{H}}_2\mathrm{O} \to \mathrm{NaOH} \stackrel{{\mathrm{CO}}_2}{\to }{\mathrm{Na}}_2{\mathrm{CO}}_3\stackrel{\mathrm{HCl}}{\to }\underset{\left(\mathrm{molten}\right)}{\mathrm{NaCl}} \stackrel{\mathrm{Electrolysis}}{\to }\mathrm{Na}$

The sodium extract of an organic compound on acidification with acetic acid and addition of lead acetate solution gives a black precipitate. The organic compound contains

• nitrogen

• halogen

• sulphur

• phosphorus

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

228.

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