Science (English Medium) कक्षा ११ - CBSE Question Bank Solutions

Which of the following statements is correct?

In DNA and RNA, nitrogen atom is present in the ring system. Can Kjeldahl method be used for the estimation of nitrogen present in these? Give reasons.

Match Column I with Column II.

Which of the following reactions of methane is incomplete combustion:

The intermediate carbocation formed in the reactions of HI, HBr and HCl with propene is the same and the bond energy of HCl, HBr and HI is 430.5 kJ mol^–1, 363.7 kJ mol^–1 and 296.8 kJ mol^–1 respectively. What will be the order of reactivity of these halogen acids?

Predict the major product (s) of the following reactions and explain their formation.

\[\ce{H3C - CH = CH2 ->[(Ph.CO.O)2][HBr]}\]

\[\ce{H3C - CH = CH2 ->[HBr]}\]

Nucleophiles and electrophiles are reaction intermediates having electron-rich and electron-deficient centres respectively. Hence, they tend to attack electron-deficient and electron-rich centres respectively. Classify the following species as electrophiles and nucleophiles.

(i) H₃CO^– 

(ii) \[\begin{array}{cc}
\phantom{.}\ce{O}\\
\phantom{.}||\\
\ce{H3C - C - O-}
\end{array}\]

(iii) \[\ce{\overset{\bullet}{C}l}\]

(iv) Cl₂C:

(v) (H₃C)₃C⁺ 

(vi) Br^– 

(vii) H₃COH

(viii) R – NH – R

Write hydrocarbon radicals that can be formed as intermediates during monochlorination of 2-methylpropane? Which of them is more stable? Give reasons.

0.3780 g of an organic chloro compound gave 0.5740 g of silver chloride in Carius estimation. Calculate the percentage of chlorine present in the compound.

In the estimation of sulphur by Carius method, 0.468 g of an organic sulphur compound afforded 0.668 g of barium sulphate. Find out the percentage of sulphur in the given compound.

Discuss the principle of estimation of halogens present in an organic compound.

\[\ce{CO}\] is isoelectronic with

(i) \[\ce{NO+}\]

(ii) \[\ce{N2}\]

(iii) \[\ce{Sncl2}\]

(iv) \[\ce{NO^{-}2}\]

Give reasons for the following:

Ethyne molecule is linear.

Assertion (A): Among the two \[\ce{O - H}\] bonds in \[\ce{H2O}\] molecule, the energy required to break the first \[\ce{O - H}\] bond and the other \[\ce{O - H}\] bond is the same.

Reason (R): This is because the electronic environment around oxygen is the same even after breakage of one \[\ce{O - H}\] bond.

Assertion (A): Sulphur present in an organic compound can be estimated quantitatively by Carius method.

Reason (R): Sulphur is separated easily from other atoms in the molecule and gets precipitated as light yellow solid.

Assertion (A): Toluene on Friedal Crafts methylation gives o– and p–xylene.

Reason (R): CH₃-group bonded to benzene ring increases electron density at o– and p– position.

Discuss the principle of estimation of sulphur present in an organic compound.

The ionisation constant of an acid, K_a, is the measure of strength of an acid. The K_a values of acetic acid, hypochlorous acid and formic acid are 1.74 × 10^–5, 3.0 × 10^–8 and 1.8 × 10^–4 respectively. Which of the following orders of pH of 0.1 mol dm^–3 solutions of these acids is correct?

Discuss the principle of estimation of phosphorus present in an organic compound.

Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298K from their solubility product constants. Determine also the molarities of individual ions.