Q27 of 30 Page 256

A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the option given below each equation.

Assertion : Bond angle in ethers is slightly less than the tetrahedral angle.


Reason : There is repulsion between the two bulky (—R) groups.


In the ether, the bond angle is greater than the tetrahedral angle due to the fact that internal repulsion by the hydrocarbon part is greater than the external repulsion of the lone pair on oxygen.


Thus, both the assertion and reason are true and the reason is the correct explanation of the assertion.

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Label the glucose and fructose units in the following disaccharide and identify anomeric carbon atoms in these units. Is the sugar reducing in nature? Explain.


 26

A statement of assertion followed by a statement of reason is given. Choose the correct answer out of the option given below each equation.

Assertion : When NaCl is added to water a depression in freezing point is observed.


Reason : The lowering of vapour pressure of a solution causes depression in the freezing point.


 28

Explain why does the enthalpy change of a reaction remain unchanged even when a catalyst is used in the reaction.

OR


With the help of an example explain what is meant by pseudo first order reaction.


 29

When a chromite ore (A) is fused with sodium carbonate in free excess of air and the product is dissolved in water, a yellow solution of compound (B) is obtained. After treatment of this yellow solution with sulphuric acid, compound (C) can be crystallised from the solution. When compound (C) is treated with KCl solution, orange crystals of compound (D) crystallise out. Identify compounds A to D and also explain the reactions.

OR


An oxide of mangnese (A) is fused with KOH in the presence of an oxidizing agent and dissolved in water. A dark green solution of compound (B) is obtained. Compound (B) disproportionates in neutral or acidic solution to give purple compound (C). Alkaline solution of (C) oxidises potassium iodide solution to a compound (D) and compound (A) is also formed. Identify compounds A to D and also explain the reactions involved.