Correct Answer: C. 6.02 x 10¹⁹

Explanation

(a) Molecular formula gives the actual number of each kind of atom in one molecule while structural formula is a graphical representation of a molecule of a compound which shows how the atoms are linked/bonded together OR Molecular formula gives the total number of atoms of each element in one molecule of a compound. while structural formula shows li arrangements/relative position of atoms/atoms and bonds in one molecule of a compound.

(b) Factors that Determine the ionization Energy of an Atom:

- Atomic radius/size of atom Nuclear charge.

- Shielding effect/screening effect.

- Electron configuration,-Penetration effect.

(c) Conditions Necessary for the Establishment of a Chemical Equilibrium

- The rates of the forward and backward reactions must be equal.

- \(\bigtriangleup\)G must be zero.

- The temperature must be constant

- System must be dynamic/ all reactant and product must be present.

- System must be closed.

(d) Consider the following table:

(i) Element B

Reason: Element B has the lowest ionization energy/ it loses electrons most easily.

(e)Graham's Law of Diffusion: Graham's law of diffusion states that the rate of diffusion of gas at the same temperature and pressure is inversely proportional to the square root of its vapor density/molar mass

(f)i. Salts that is/are readily soluble in water: - Mg(NO\(_{3}\))\(_{2}\), Na\(_{2}\)SO\(_{4}\)

(ii) Insoluble in Water - CaCO\(_{3}\)

(g) Product classification as addition polymer or condensation polymer:

(i) Protein - Condensation.

(ii) Perspex - Addition.

(iii) Nylon - Condensation.

(h) Define Atomic Radius:

- lt is defined as half the distance between the nuclei of any two close atoms in a molecule/or is a measure of the size of its atoms, the mean distance from the center of the nucleus to the boundary of the surrounding shells of electrons.

(i) Why ethanol has a higher boiling point than propane even though they both have comparable molar mass: - The intermolecular forces in ethanol are hydrogen bonds which are stronger than the van der Waal's forces in propane.

(j) Three Significance of pH Value in Everyday Life:

- Digestion of food.

- Determination ofpHof soil/used in agriculture.

- Important role in the survival of animals (self-defense) existence of living beings.

- pH change as the cause of tooth decay.

- Treatment of water for public supply.

- reatment of industrial efluent/ liquid waste.

- ln pharmaceuticals.

- In medicine (to determine pH of body fluid/urine /blood).

Correct Answer: D. dissolve in polar solvent

Correct Answer: A. ionic

Correct Answer: B. acidified KMnO₄

Correct Answer: A. Joseph J. Thompson

Correct Answer: D. NO₂

Explanation

Acid rain results when sulfur dioxide (SO2) and nitrogen oxides (NOX) are emitted into the atmosphere and transported by wind and air currents. The SO2 and NOX react with water, oxygen and other chemicals to form sulfuric and nitric acids

Correct Answer: D. Gaining one electron

Correct Answer: D. decreases down the group

Explanation

(a)i. Characteristics of homologouS series

- All members can be represented by a general formula.

- Each member of the series differs from the next by a constant/fixed number of atoms

- CH\(_{2}\)/ 14 amu

- All members of the series show a gradual change in physical properties such as density.

- AII members have similar chemical properties/same functional groups.

- All members of the group are prepared using a similar chemical method

(ii) Differences in the Reaction of Ethane and Ethene

- Ethane is a saturated hydrocarbon containing a single bond and therefore undergoes mainly substitution reaction while ethene is an unsaturated hydrocarbon containing a double bond and hence undergoes an addition reaction

(b)i. The gas is hydrogen chloride.

(ii) Physical properties of the gas:

- Colourless

- Has choking smell

- Denser than air

- Gas is soluble in water.

- Gas fumes in moist air.

(iii) Write a balanced equation reaction:

2HaCl\(_{(s)}\) + H,SO\(_{4(aq)}\), \(\implies\) Na2SO\(_{4(aq)}\) + 2HC\(_{(g)}\) OR HaCI\(_{(s)}\) + H\(_{2}\)SO\(_{4(aq)}\) \(\implies\) NaHSO\(_{4(aq)}\) + HCl\(_{(g)}\)

(c)i. Hydrocarbons are compounds containing only hydrogen and carbon

(ii) Two Natural Sources of Hydrocarbons:

- Coal

- Petroleum/crude oil Natural gas.

(iii) A hydrocarbon contains 83.0 % of carbon by mass. calculate its emprical formular (H =1.0; C = 12.0).

Solution: C = 83.0 %.

\(\therefore\) % H\(_{2}\) = 100 - 83 17%

(d) Draw and label a diagram of a set-up that could be used to electroplate a copper ornament with silver.