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(a)(i) Covalent bond is a bond between two atoms in which each of the atoms contribute to the shared pair of electrons. (ii) (a) Non-conductors of electricity (b) Insoluble in water/soluble in non-polar solvents. (c) Have low melting or boiling point. (v) (a) covalent bond (b) covalent bond dative or coordinate covalent bond (b) Particles Relative Masses Proton Proton 1 Neutron 1 Electron 1 1840 (c)(i) Graham's law of diffusion states that a constant temperature and pressure, the rate of diffusion of a gas is inversely proportional to the square root of its vapour density or molecular mass. (ii) N\(_2\), CH\(_4\), He : the smaller the molecular mass the faster the rate at which the gas diffuses or the larger the molar mass the slower the rate at which the gas diffuses. (d)

(a)(i) Oxide of non-metals which dissolve in water to form acidic solution. (ii) 1. Acidic oxides:- SO\(_2\)/CO\(_2\)/NO\(_2\), etc. 2. Basic oxides:- CaO/Na\(_2\)O/K\(_2\)O, etc. 3. Amphoteric oxides:- Al\(_2\)O\(_3\)/ZnO/PbO, etc. 4. Neutral oxides:- CO/N\(_2\)O, etc. (b)(i) Heat of combustion is the heat change when one mole of a substance is completely burnt in oxygen or burnt in excess oxygen (ii) Heat of neutralization is the heat change when one mole of water is produced as a result of a reaction between an acid and alkali in dilLte solution or the heat change when one mole of H+ from an acid reacts with one mole of OH\(^-\) from an alkali to form one mole of H\(_2\)O. (ii)1. C\(_{(g)}\) + O\(_{2(g)}\) \(\to\) CO\(_{2(g)}\) 2. HaOH\(_{(aq)}\) + HCl\(_{(aq)}\) \(\to\) NaCI + H\(_2\)O\(_{(l)}\) \(\Delta\) Hn\(^o\) 3. Molar mass of C\(_4\)H\(_{10}\) = 12 x 4 + 1 x 10 = 48 + 10 = 58g mol\(^{-1}\) . 58g of C\(_4\)H\(_{10}\) = 5877kJ mol\(^{-1}\) 14.5 of C\(_4\)H\(_{10}\) = \(\frac{5877 \times 14}{58}\) kJ mol\(^{-1}\) = + 1469.25 kJ. (c)(i) Rhombic Monoclinic Rhombic Monoclinic Yellow translucent crystal Transparent amber crystal Stable at temperature below 96^\circC Unstable at temperature below 96^\circC Higher density than monoclinic Lower density than rhombic Lower melting point Higher melting point Octahedral shaped Needle shaped. (d)(i)(a) They are monoatomic gases (b) They are chemically unreactive (c) Have low melting/boiling point. (ii) He — filling balloons. Ar — arc welding.

(a)(i) Hard water is water which will not readily form lather with soap. (ii) 1. Calcium tetraoxosulphate (IV) 2. Calcium hydrogen trioxocarbonate (IV) 3. Magnesium tetraoxosulphate (VI) 4. Magnesium hydrogen trioxocarbonate (IV). (iii)(a) Heating the water to boiling/distillation (b) Addition of calculated amount of calcium hydroxide [Ca(OH)\(_2\)] (c) Addition of washing soda crystals to the water [Na\(_2\)CO\(_3\)] (d) Ion exchange resin/permutit method. (b)(i) Sulphur air or oxygen (ii) 2SO\(_{2(g)}\) +O\(_{2(g)}\) \(\rightleftharpoons\) 2SO\(_{3(g)}\) (iii) V\(_2\)O\(_5\) / Vanadium (V) oxide. (c)(i) Use of Na\(_2\)SO\(_4\) (a) Water softener (b) In glass or paper manufacturing (c) As analytical reagent (d) As purgative (e) In the manufacture of detergents . (ii) Mass of salt per 30 cm\(^3\) of saturated solution = 1.80g. 1000 cm\(^3\) of saturated solution contains = \(\frac{1000 \times 1.80}{30}\) = 60g. Molar mass of Na\(_2\)CO\(_3\) = 23 x 2 + 12 x 1 + 16 x 3 = 106g. Solubility of Na\(_2\)CO\(_3\) = \(\frac{60}{106}\) = 0.566 mole dm\(^3\). (d)(i) Activated complex is the intermediate (complex) that reactants must attain in order to form a product or it is a temporary species formed by reactant molecules as a result of collision before the products are formed. (ii) A collision may fail to produce a chemical reaction if the energy of the colliding particles is less than activation energy / if the reactant are not properly aligned.

According to Le Chatelier's Principle, this will be favored if you lower the temperature. The system will respond by moving the position of equilibrium to counteract this - in other words by producing more heat. To get as much ammonia as possible in the equilibrium mixture, you need as low a temperature as possible

(a)(i) Q is copper (II) trioxocarbonate (IV) (ii) R is carbon (IV) oxide (iii) Excess Q was used to ensure that all the acid reacted (iv) When there is no more effervescence. (v) Filtration. (b)(i) White anhydrous copper (II) teraoxosulphate (VI). (ii) Alkaline iodine solution, or acidified potassium tetraoxomanganate (VIl).

Test Observation Inference (a) C + water Mixture filtered Filtrate 1 litmus Partly dissolves Colourless filtrate white residue No effect on litmus C contains solution and insoluble salts Filtrate is neutral (b)(i) Filtrate + dil. H\(_2\)SO\(_4\) + AgNO\(_{3(aq)}\) (ii) Mixture in (b)(i) + excess NH\(_3\) soln No reaction white ppt ppt dissolves Cl\(^-\) present Cl\(^-\) confirmed (c) Residue + dil. HNO\(_3\) Effervescence occurs, gas turns lime water milky CO\(_2\) CO\(_3^{2-}\) present (d)(i) First portion + dil. NH\(_3\) in drops then in excess (ii) Second portion + dil. HCl White ppt ppt insoluble White chalky ppt Pb\(^{2+}\) may be present Pb\(^{2+}\) present Pb\(^{2+}\) confirmed

Table of Result Indicator used: Phenolphthalein Volume of pipette = 25 cm\(^3\) Burette Reading Rough 1st 2nd 3rd Final (cm\(^3\)) 22.60 22.40 22.30 22.30 Initial (cm\(^3\)) 0.00 0.00 0.00 0.00 Volume of acid used (cm\(^3\)) 22.00 22.40 22.30 22.30 Average volume of acid used, V\(_A\) = \(\frac{22.40 + 22.30 + 22.30}{3}\) = \(\frac{67.00}{3}\) Average titre value = 22.30 cm\(^3\), V\(_A\) (b)(i) Amount of acid in the average titre, V\(_A\) 1000 cm\(^3\) contains 0.05 moles V\(_A\) will contain = \(\frac{0.05 \times 22.30}{1000}\) = 0.0011 moles (ii) Concentration of NaOH in B \(\frac{0.025}{0.25}\) = 0.199 mol dm\(^{-3}\) To calculate the amount of base in 25 cm\(^3\) \(\frac{25 cm^3}{1000}\) x 0.100 mol dm\(^{-3}\) = 0.0025 moles (iii) Mole ratio of acid (H\(_y\)X) to base (NaOH) \(\frac{0.0011}{0.0025}\) = \(\frac{1}{2}\) (c) Equation for the reaction 2NaOH + H\(_y\)X \(\to\) Na\(_2\)X + H\(_2\)O (d) Basicity of acid H\(_y\)X = 2, (two)

Sodium chloride, which is obtained by neutralization of hydrochloric acid and sodium hydroxide, is a neutral salt. A neutral salt is formed when a strong acid reacts with a strong base. This is because the strong acid is completely neutralized by the strong base. When a strong acid and a strong base are combined in the right amounts, the result is a neutral solution with a pH of 7. The acid and base have neutralized each other, and the acidic and basic properties are no longer present. The salt formed from a strong acid and a strong base is neutral because the anion and cation are both weak. They are stable in water and do not react with water to form the original acid or base.

Elements in period 3 have 3 shells in their atomic structure. These include elements from sodium to argon.

This is called hydrogenation. It includes the manufacture of margarine from animal or vegetable fats and oils. Ethene reacts with hydrogen in the presence of a finely divided nickel catalyst at a temperature of about 150^\circC. Ethane is produced.

Nitric acid is not used in the preparation of hydrogen because it is a strong oxidizing agent, meaning it readily oxidizes the hydrogen gas produced during the reaction with a metal, converting it to water and thus preventing the collection of hydrogen gas; instead, acids like dilute hydrochloric acid or sulphuric acid are preferred for hydrogen production as they do not oxidize hydrogen.

Nitrogen prevents food from degrading by creating an unreactive atmosphere. Aluminium is used in buildings because it's resistant to corrosion and thermally efficient. Copper is a versatile metal used in many applications, including electrical wiring, plumbing, construction, and transportation. Sulphur is commonly used as an ingredient in the head of a match, contributing to its ability to ignite easily when struck against a striking surface; most modern safety matches contain sulfur or charcoal alongside other chemicals like potassium chlorate and antimony sulphide. Sulphur acts as a fuel in the match head, readily combusting when combined with an oxidizer like potassium chlorate.

When calcium oxide (CaO) reacts with carbon (C), it produces calcium carbide (CaC\(_2\))and carbon monoxide (CO). This reaction occurs at very high temperatures, around 700^\circC. CaO + 3C → CaC\(_2\) + CO

A solution containing carbonate when treated with hydrochloric acid, produces a colourless, odourless gas (carbon dioxide) that turns lime water milky. For example, when hydrochloric acid (HCl) reacts with sodium carbonate (Na\(_2\)CO\(_3\)), it releases carbon dioxide (CO\(_2\)) gas, which is colourless and odourless.

An alloy is a mixture of chemical elements of which in most cases at least one is a metallic element, although it is also sometimes used for mixtures of elements; The soft solder used for welding and plumbing is alloy of Tin and Lead. The mixture of tin and lead creates a eutectic alloy, meaning it has a lower melting point than either metal alone, making it easy to work with and join metal parts together without excessively heating the base material, making it ideal for delicate applications like plumbing joints and electrical connections.