(a) i) Give the name and nature of the radiations that are emitted during radioactivity.
ii) State two differences between chemical reaction and nuclear reaction.
iii) Balance the following nuclear reactions and identify X and Y.
I. \(^{212}_{84} PO\) \(\to\) \(^{208}_{82} Pb\) + X
II \(^{137}_{55}Cs\) \(\to\) \(^{137}_{55}Ba\) + Y
(b) The electron configuration of an element X is: 1s\(^2\) 2s\(^2\) 2p\(^6\) 3s\(^2\) 3p\(^5\)
(i) Deduce the atomic number of X.
(ii) To what group does X belong?
(iii) Give two properties of the group to which the element X belong.
(iv) Identify element X by name.
(v) Write a balanced equation to represent the reaction between the element X and hot concentrated NaOH.
(c)(i) Explain why: I. graphite is used as a lubricant; II. diamond is used as an industrial cutting tool.
(ii) Write an equation to represent the reaction between aqueous HCI and NH\(_3\) solution.
(iii) Name the type of reaction represented by the equation.
Explanation
(a)(i)- alpha particle, (doubly charged) helium nucleus/high ionizing/low penetrating power/deflected towards negative plate.
- beta particle, (fast moving) electron/moderate ionizing/moderate penetrating power/deflected towards positive plate.
- gamma radiation, (high energy) electromagnetic radiation/low ionizing/high penetrating power effect in magnetic field.
(ii)
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Chemical Reaction |
Nuclear Reaction |
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- atoms are rearranged by the breaking and forming of chemicarbondlno new atom is formed/atomic number or mass number of each element does not change. - only (valence) electrons are involved. - reactions are accompanied by absorption /release of (relatively) small amount of energy. - rate of reaction is influenced by temperature, pressure, concentration and catalyst.
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- elements are converted to other elements/new elements may be formed/atomic number or mass number of each element may change - protons, neutrons, electrons and other elementary particles may be involved.
- reactions are accompanied by release of (relatively) large amount of energy. - rate of reaction normally is not affected by pressure, temperature and catalyst.
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(iii) I. \(^{212}_{84}Po\) \(to\) \(^{208}_{82}Pb\) + \(^{4}_2X\) (X is \(\alpha\)-particle/helium nucleus/\(^{4}_2He\))
II. \(^{137}_{55}Cs\) \(\to\) \(^{137}_{56}Ba\) + \(^{0}_{-1}Y\) (Y is \(\beta\)-particle/electron/ \(^{0}_{-1}He\))
(b).(i) atomic number = 17
(ii) group 7
(iii) - formation of diatomic molecules. - formation of monovalent ions/same valence electrons, - they are coloured substances. - they are oxidizing agents., - most electronegative in its period/smallest atomic size in its period. - they are non-metals.
(iv) chlorine .
(v) 3Cl\(_2\) +6NaOH ----> 5NaCl + NaCIO\(_3\) + 3H\(_2\)O.
(c)(i) I. Graphite consists of planar layers (in which all carbon-carbon bonds extend in two dimensions) which can slide over each other. Hence it is used as lubricant.
II. Diamond consist of (large) three dimensinoal network of carbon-carbon bonds which Makes it hard hence, used as a cutting tool.
(ii) HCI\(_{aq}\) + NH\(_{3(aq)}\) --> NH\(_4\)CI\(_{(aq)}\)
OR HCI\(_{aq}\) + NH\(_4\)HO\(_{aq}\) --> NH\(_4\)Cl\(_{aq}\) + H\(_2\)O\(_{l}\)
(iii) Combination OR Neutralisation.