Science (English Medium) कक्षा १२ - CBSE Question Bank Solutions

Assertion: \[\ce{SF6}\] cannot be hydrolysed but \[\ce{SF4}\] can be.

Reason: Six \[\ce{F}\] atoms in \[\ce{SF6}\] prevent the attack of \[\ce{H2O}\] on sulphur atom of \[\ce{SF6}\].

\[\begin{array}{cc}
\ce{CH3 - C ≡ CH ->[40{%} H2SO4][1{%} HgSO4] A ->[Isomerisation] CH3 - C - CH3}\\
\phantom{........................................}||\\
\phantom{........................................}\ce{O}\\
\end{array}\]

Structure of ‘A’ and type of isomerism in the above reaction are respectively.

Arenium ion involved in the bromination of aniline is:

(i)

(ii)

(iii)

(iv)

Why is benzene diazonium chloride not stored and is used immediately after its preparation?

Why does acetylation of –NH₂ group of aniline reduce its activating effect?

Predict the product of reaction of aniline with bromine in non-polar solvent such as \[\ce{CS2}\].

Why is aniline soluble in aqueous HCl?

How will you carry out the following conversions?

toluene `->` p-toluidine

How will you carry out the following conversions?

p-toluidine diazonium chloride `→` p-toluic acid

Match the compounds given in Column I with the items given in Column II.

A colourless substance ‘A’ \[\ce{(C6H7N)}\] is sparingly soluble in water and gives a water soluble compound ‘B’ on treating with mineral acid. On reacting with \[\ce{CHCl3}\] and alcoholic potash ‘A’ produces an obnoxious smell due to the formation of compound ‘C’. Reaction of ‘A’ with benzenesulphonyl chloride gives compound ‘D’ which is soluble in alkali. With \[\ce{NaNO2}\] and \[\ce{HCl}\], ‘A’ forms compound ‘E’ which reacts with phenol in alkaline medium to give an orange dye ‘F’. Identify compounds ‘A’ to ‘F’.

Predict the reagent or the product in the following reaction sequence.

Discuss briefly, giving an example of the role of coordination compounds in biological systems.

Account for the following:

Ti(IV) is more stable than the Ti (II) or Ti(III).

What is meant by the chelate effect? Give an example.

Draw the structure of the following compound.

3-Bromo-4-phenylpentanoic acid

What is meant by the chelate effect? Give an example.

Draw the structure of the following compound.

3-Bromo-4-phenylpentanoic acid

What is meant by the chelate effect? Give an example.