Q. 1. (a) Why do thermonuclear reactions require very high temperature?
(b) One of the hazards of nuclear explosion is the generation of Sr-90 and its subsequent Incorporation in bones. This nuclide has a half-life period of 28.1 years. Suppose one microgram was absorbed by a newborn baby, how much Sr-90 will remain in his bones after 20 years? 3

Q. 2. Write four characteristic features of enzymes Name a disease which is caused by the deficiency of a particular enzyme. 3

Q. 3. Account for the following: 5
(a) Sn (II) is a reducing agent but Pb (II) is not.
(b) PH₃ Is a weaker base than NH ₃ .
(c) SF₆ exists but SH ₆ does not
(d) Sulphur exhibits tendency for catenation but oxygen does not
(e) The electron affinity of fluorine is less than that of chlorine.

Q. 4. (a) Explain the cause and consequences of lanthanide contraction.
(b) Give balanced chemical equations for the following reactions:
(i) Between acidified potassium dichromate and potassium Iodide.
(ii) Between potassium permanganate and oxalic acid In the presence of dilute sulphuric acid
(iii) Chromite ore is fused with NaOH in air.

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