(a) Atoms of four non-metallic elements in the same group of the periodic table are arranged in order of increasing atomic radius as R < T < W < X. Which of the elements (i) would readily lose electron(s) from the outermost shell; (ii) is most electronegative; (iii) would T displace from aqueous solution; (iv) is at the top of the group?
(b) The following table shows the electronic configuration of two elements Y and Z.
Element
Electronic Configuration
Y
1s\(^2\) 2s\(^2\) 2p\(^5\)
Z
1s\(^2\) 2s\(^2\) 2p\(^5\) 3s\(^1\)
(i) Name the I. group to which Y belongs II. period to which Z belongs. (ii) What is the number of protons present in an atom of Z? (iii) How many unpaired electrons are in an atom of Y? (iv) Write the formula of the compound formed between Y and Z
(c) Name the type of bond(s) that exist(s) in each of the following compounds. (i) CaCl\(_2\); (ii) NH\(_4\)Cl; CCl\(_4\)
(d) Describe how the conductance of a molar solution of ammonia compares to that of sodium hydroxide solution. (e) State the type of reaction illustrated by each of the following equations: (i) CH\(_3\)CH\(_2\)OH\(_{(/)}\) + CH\(_3\)COOH\(_{(aq)}\) \(\rightleftharpoons\) CH\(_3\)COOC\(_2\)H\(_5\)\(_{(/)}\) + H\(_2\)O\(_{(/)}\) (ii) H+\(_{Y^+_{(aq)}\) + OH\(^+_{(aq)}\) \(\to\) H\(_2\)O
(f) Determine the volume of the residual gas when 20.0cm\(^3\) of hydrogen was sparked with 15.0cm\(^3\) of oxygen and the resulting mixture cooled to room temperature.
Explanation
(a)(i) X (ii) R (iii) VV and X (iv) R (b) (i) I. group VII II. period III (ii) eleven (iii) one (iv) ZY.
(c) (i) ionic/electrovalent bond (ii) covalent co-ordinate covalent and ionic (iii) covalent.
(d) - pour some quantity of each solution into a separate beaker. - insert electrodes into the solutions and close the circuit. take the readings on the ammeter. - rinse the electrodes properly with distilled water and dip them into the second solution. Close the circuit and take the reading on the ammeter again. - the solution with the higher reading is NaOH\(_{(aq)}\) while the one with lower reading is ammonia. OR NaOH solution is a strong electrolyte and completely ionizes to produce a lot of ions. NH\(_3\) solution is a weak electrolyte and produces very few ions. The ions produced by NaOH far out-number those produced by NH\(_3\) solution. Hence NaOH solution conducts more than NH\(_3\) solution. (e) (i) Esterification (ii) Neutralization. (f) 2H\(_2(g)\) + O\(_{2(g)}\) —> 2H\(_2\)O (I) from the equation 2 vols of H\(_2\) reacts with 1 vol. of O\(_2\)/ 20cm\(^3\) of H\(_{2(s)}\) reacts with 10cm\(^3\) of O\(_{2(g)}\) residual gas = (15 — 10)cm\(^3\) = 5cm\(^3\) .
