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

Although Zr belongs to 4d and Hf belongs to 5d transition series but it is quite difficult to separate them. Why?

Although +3 oxidation states is the characteristic oxidation state of lanthanoids but cerium shows +4 oxidation state also. Why?

Match the compounds/elements given in Column I with uses given in Column II.

Match the statements given in Column I with the oxidation states given in Column II.

Match the property given in Column I with the element given in Column II.

On the basis of Lanthanoid contraction, explain the following:

Nature of bonding in \[\ce{La2O3}\] and \[\ce{Lu2O3}\] .

On the basis of Lanthanoid contraction, explain the following:

Trends in the stability of oxo salts of lanthanoids from \[\ce{La}\] to \[\ce{Lu}\].

On the basis of Lanthanoid contraction, explain the following:

Stability of the complexes of lanthanoids.

On the basis of Lanthanoid contraction, explain the following:

Radii of 4d and 5d block elements.

On the basis of Lanthanoid contraction, explain the following:

Trends in acidic character of lanthanoid oxides.

Match the reactions given in Column I with the names given in Column II.

	Column I	Column II
(i)		(a) Fittig reaction
(ii)		(b) Wurtz Fittig reaction
(iii)		(c) Finkelstein reaction
(iv)	\[\ce{C2H5Cl + Nal ->[dry acetone] C2H5l + NaCl}\]	(d) Sandmeyer reaction

Assertion: tert-Butyl bromide undergoes Wurtz reaction to give 2, 2, 3, 3-tetramethylbutane.

Reason: In Wurtz reaction, alkyl halides react with sodium in dry ether to give hydrocarbon containing double the number of carbon atoms present in the halide.

Preparation of alcohols from alkenes involves the electrophilic attack on alkene carbon atom. Explain its mechanism.

Explain why low molecular mass alcohols are soluble in water.

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

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

Amino acids are classified as acidic, basic or neutral depending upon the relative number of amino and carboxyl groups in their molecule. Which of the following are acidic?

(i)

\[\begin{array}{cc}
\ce{(CH3)2CH - CH - COOH}\\
\phantom{..}|\\
\phantom{.....}\ce{NH2}
\end{array}\]

(ii)

\[\begin{array}{cc}
\ce{HOOC - CH2 - CH2 - CH - COOH}\\
\phantom{............}|\\
\phantom{...............}\ce{NH2}
\end{array}\]

(iii)

\[\ce{H2N - CH2 - CH2 - CH2 - COOH}\]

(iv)

\[\begin{array}{cc}
\ce{HOOC - CH2 - CH - COOH}\\
\phantom{.....}|\\
\phantom{........}\ce{NH2}
\end{array}\]

Assertion: Glycine must be taken through diet.

Reason: It is an essential amino acid.

Which of the following polymers have vinylic monomer units?

(i) Acrilan

(ii) Polystyrene

(iii) Nylon

(iv) Teflon

How is the following resin intermediate prepared and which polymer is formed by this monomer unit?

 (Resin intermediate)

Match the polymers given in Column I with their commercial names given in Column II.