(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.