(a) What is the shape of (i) p - orbital; (ii) a molecule of methane; (iii) a molecule of carbon (IV) oxide?
(b) Consider the following elements: Ne, S, CI, 0, Fe, Mg. State which of them (i) exhibit(s) allotropy; (ii) form(s) coloured ions; (iii) is/are malleable; (iv) consist(s) of molecules that are far apart at room temperature; (v) form(s) hydrides by sharing electrons with hydrogen; (vi) has/have complete outermost shell.
(c)(i) List three applications of radioactivity in different fields. (ii) Explain clearly the difference between the following reactions involving electron loss from lead. \(^{211} pb\) \(\to\) \(^{ 211}Bi\) + \(^0_{-1}\); Pb \(\to\) pb\(^{3+}\) _ 2e\(^-\) (iii) Give one advantage and one disadvantage of nuclear power generation over the use of fossil fuels.
Explanation
(a)(i) P=orbital are mutually perpendicular dumb-bell shaped lobes. (ii) Methane is tetrahedral (iii) Carbon (IV) oxide is linear.
(b)(i) Sulphur exhibits allotropy (ii) Fe (iii) Fe and Mg (iv) Ne, CI, O (v) Mg (vi)Ne.
(c)(i) —Medical uses — Sterilization — Industrial uses —Agricultural purposes — Radioactive tracers — Dating techniques (ii) \(^{211} pb\) \(\to\) \(^{ 211}Bi\) + e is a radioactive reaction. It involves the production of beta particles and transmutation of Pb to Bi. Pb --> Pb\(^{2+}\) + 2e\(^-\) is an ionisation reaction where Pb lost two electrons (oxidation) to become Pb\(^{2+}\). (iii) Advantage: Nuclear power generation can work day and night for a few years with the same uranium fuel. Disadvantage: It is too expensive to install when compared with fossil fuels.
