Compounds having general molecular formula  \(AFe_{ 2 }O_{ 4 }\) are called ferrites and posses spinel type structures. Some common examples are \(MgFe_{ 2 }O_{ 4 }\)  and \(ZnFe_{ 2 }O_{ 4 }\) They may be thought of being formed by replacing \(Fe^{ 2+ }\) ions present in \(Fe_{ 3 }O_{ 4 }\) by bivalent cations such as \(Mg^{ 2+ },Zn^{ 2+ }\) ions etc. Now answer the following questions :
(i) What types of materials are ferrites?
(ii) What are the main uses of ferrites?

(a)  Differentiate between molarity and molality for a solution. How does a change in temperature influence their values?
(b) Calculate the freezing point of an aqueous solution containing 10.50 g of MgBr₂ = 184 g) (K _f for water 1.86 K kg mol^-1)

Using the standard electrode potentials, predict if the reaction between the following is feasible:
(i) Fe³⁺(aq) and I^-(aq)
(ii) Ag⁺(aq) and Cu(s)
(iii) Fe³⁺(aq) and Br^-(aq) 
(iv) Ag(s) and Fe³⁺(aq)
(v) Br₂(aq) and Fe²⁺(aq)

Mira's house had a fencing of iron rods. Her father suggested getting it painted. But she and her mother thought it was a waste of time and money as iron rods are strong:
(i) Whose opinion is acceptable according to you?
(ii) Give two other methods to prevent corrosion.
(iii) What is the chemical formula of rust?
(iv) Mention the values shown by Mira's father.

(i) For the reaction A➝B, the rate of reaction becomes twenty-seven times when the concentration of A is increased three times. What is the order of the reaction?
(ii) The activation energy of a reaction is 75.2 kJ mol^-1 in the absence of a catalyst and it lowers to 50.14 kJ mol^-1 with a catalyst. How many times will the rate of reaction grow in the presence of a catalyst if the reaction proceeds at 25°C?

(a) Given below are the electrode potential values, E^o for the some of the first row of transition elements:

Explain the irregularities in these values on the basis of electronic structures of atoms.
(b) Complete the following reaction equations:
(i) Cr₂O₇^2-+Sn²⁺+H⁺\(\longrightarrow \) 
(ii) MnO₄^-+Fe²⁺+H⁺\(\longrightarrow \)

(a) Define the following terms:
(i) Mole fraction,
(ii) Ideal solution.
(b) 15.0 g of an unknown molecular material is dissolved in 450 g of water. The resulting solution freezes at - 0.34 \(°\)C. What is the molar mass of the material? [K_f for water=1.86 K Kg mol^-1]

A compound A (C₄H₁₀O) is found to be soluble in concentrated sulphuric acid. (A) does not react with sodium metal or potassium permanganate. When (A) is heated with excess of HI, it gives a single alkyl halide. Deduce the structure of compound (A) and explain all the reactions involved.

An organic compound (A) on treatment with ethyl alcohol gives a carboxylic acid (B) and compound (C). Hydrolysis of (C) under acidified conditions gives (B) and (D). Oxidation of (D) with KMnO₄ also gives (B). (B) on heating with Ca(OH)2 gives (E) having moleuclar formula C₃H₆O. (E) does not give TOllens'test and does not reduce Fehiling's solution but forms 2, 4-dinitrophenyhydrazone. Identify (A),(B),(C),(D) and (E).