Science (English Medium) Class 12 - CBSE Question Bank Solutions for Chemistry

Answer the following question:

Which element of the first transition series has lowest enthalpy of atomisation?

Identify the metal and justify your answer.

Carbonyl \[\ce{M(CO)5}\]

Identify the metal and justify your answer.

\[\ce{MO3F}\]

Mention the type of compounds formed when small atoms like H, C and N get trapped inside the crystal lattice of transition metals. Also give physical and chemical characteristics of these compounds.

Transition metals can act as catalysts because these can change their oxidation state. How does \[\ce{Fe(III)}\] catalyse the reaction between iodide and persulphate ions?

Mention any three processes where transition metals act as catalysts.

A violet compound of manganese (A) decomposes on heating to liberate oxygen and compounds (B) and (C) of manganese are formed. Compound (C) reacts with KOH in the presence of potassium nitrate to give compound (B). On heating compound (C) with conc. \[\ce{H2SO4}\] and \[\ce{NaCl}\], chlorine gas is liberated and a compound (D) of manganese along with other products is formed. Identify compounds A to D and also explain the reactions involved.

Write a test to detect the presence of double bond in a molecule.

Discuss the nature of C – X bond in the haloarenes.

Assertion: Nitration of chlorobenzene leads to the formation of m-nitrochlorobenzene.

Reason: –NO₂ group is a m-directing group.

What is the structure and IUPAC name of glycerol?

When phenol is treated with bromine water, white precipitate is obtained. Give the structure and the name of the compound formed.

Write the structures of the isomers of alcohols with molecular formula \[\ce{C4H10O}\]. Which of these exhibits optical activity?

Explain why is \[\ce{O = C =O}\] nonpolar while \[\ce{R - O - R}\] is polar.

The letters ‘D’ or ‘L’ before the name of a stereoisomer of a compound indicate the correlation of configuration of that particular stereoisomer. This refers to their relation with one of the isomers of glyceraldehyde. Predict whether the following compound has ‘D’ or ‘L’ configuration.

Assertion: All naturally occurring α-aminoacids except glycine are optically active.

Reason: Most naturally occurring amino acids have L-configuration.

Which of the following are addition polymers?

(i) Nylon

(ii) Melamine formaldehyde resin

(iii) Orlon

(iv) Polystyrene

Which of the following polymers are condensation polymers?

(i) Bakelite

(ii) Teflon

(iii) Butyl rubber

(iv) Melamine formaldehyde resin

Which of the following compounds are administered as antacids?

(i) Sodium carbonate

(ii) Sodium hydrogen carbonate

(iii) Aluminium carbonate

(iv) Magnesium hydroxide

What are antagonistic drugs?