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

Give one example each of sol and gel.

Write equations of the following reactions:
Acetylation of aniline

An unripe mango placed in a concentrated salt solution to prepare pickle, shrivels because ______.

Consider the figure and mark the correct option.

Water retention or puffiness due to high salt intake occurs due to ______.

Why are aquatic species more comfortable in cold water in comparison to warm water?

When kept in water, raisin swells in size. Name and explain the phenomenon involved with the help of a diagram. Give three applications of the phenomenon.

How will you distinguish between dispersed phase and dispersion medium in an emulsion?

In the preparation of \[\ce{H2SO4}\] by Contact Process, why is \[\ce{SO3}\] not absorbed directly in water to form \[\ce{H2SO4}\]?

Write the structure of pyrophosphoric acid.

Match the formulas of oxides given in Column I with the type of oxide given in Column II and mark the correct option.

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