Biomolecules — Chemistry STD 12 Science — Question

Explain Hoffmann bromamide degradation reaction with mechanism.

A colourless substance 'A' (C₆H₇N) is sparingly soluble in water and gives a water soluble compound 'B' on treating with mineral acid. On reacting with 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 NaNO₂ and HCl, 'A' forms compound 'E' which reacts with phenol in alkaline medium to give an orange dye 'F'. Identify compounds 'A' to 'F'.

Give reasons for the following:
On electrolysis in acidic solution amino acids migrate towards cathode, while in alkaline solution these migrate towards anode.

Explain the structure of starch and cellulose.

How does colour appear in coordination compounds? Its explanation is based on crystal field theory.

Answer the following questions:

For M²⁺/M and M³⁺/M²⁺ systems, E° values for some metals are as follows:

Cr2+/Cr = - 0.9 V	Cr3+/Cr2+ = - 0.4 V
Mn2+/Mn = 0 1.2 V	Mn3+/Mn2+ = +1.5 V
Fe2+/Fe = - 0.4 V	Fe3+/Fe2+ = +0.8 V

Use this data to comment upon:

1. The stability of Fe³⁺ in acid solution as compared to that of Cr³⁺ and Mn³⁺.
2. The ease with which iron can be oxidised as compared to the similar process for either Cr or Mn metals.

Match the items given in Column I and Column II.

	Column I		Column II
i.	Saturated solution	a.	Solution having same osmotic pressure at a given temperature as that of given solution.
ii.	Binary solution	b.	A solution whose osmotic pressure is less than that of another.
iii.	Isotonic solution	c.	Solution with two components.
iv.	Hypotonic solution	d.	A solution which contains maximum amount of solute that can be dissolved in a given amount of solvent at a given temperature.
v.	Solid solution	e.	A solution whose osmotic pressure is more than that of another.
vi	Hypertonic solution	f.	A solution in solid phase.

Explain the properties and uses of methanol and ethanol.