Biomolecules — Chemistry STD 12 Science — Question

How to determine the vapour pressure and total pressure of the components in binary solution of two volatile liquids? Explain their mathematical form and also explain the graph between mole fraction and vapour pressure for an ideal solution.

1. Write the steps involved in the preparation of: 

1. K₂Cr₂O₇ from Na₂CrO_4.
2. KMnO₄ from  K₂MnO_4.
3. Calomel from corrosive sublimate.

2. What is meant by lanthanoid contraction? What effect does it have on the chemistry of the elements which follow lanthanoids?

An aromatic compound ‘A’ on treatment with CHCl₃/ KOH gives two compounds ‘B’ and ‘C’. Both B and C give the same product ‘D’ when distilled with zinc dust. Oxidation of D gives E having molecular formula C₇H₆O₂. The sodium salt of E on heating with sodalime gives F which may also be obtained by distilling A with zinc dust. Identify A to F.

What is called a battery? Explain its characteristics and describe dry cell and mercury cell.

1. Define the following terms:

1. Co-enzymes.
2. Mutation in biomolecules.
3. Nucleotides.

2. List four main functions of carbohydrates in organisms.

Describe the mechanism of replication of DNA.

Discuss the different chemical properties of amines.

1. Differentiate between molarity and molality for a solution. How does a change in temperature influence their values?
2. Calculate the freezing point of an aqueous solution containing10.50g of MgBr₂ in 200 g of water. (Molar mass of MgBr₂ = 184 g)

(K_f for water = 1.86 K kg mol^–1)