2011 JAMB CHEMISTRY PAST QUESTIONS AND ANSWERS

$$\text{The question Paper Type refers to the unique code for each exam version, helping candidates identify the exact questions they answered.}$$

$$\text{Calculate molar mass of NaOH = 23 + 16 + 1 = 40. Molarity} = \frac{2}{40 \times 0.1} = 0.5 \, \text{mol dm}^{-3}.}$$

$$\text{Orderliness of particles is not peculiar to matter, as it varies based on state. In gases, particles are randomly arranged and in constant motion.}$$

$$\text{In chromatography, components move at different speeds along the column, allowing separation based on their interactions with the stationary and mobile phases.}$$

$$\text{An ideal gas exhibits low attraction between molecules and obeys gas laws under standard conditions.}$$

$$\text{In the periodic table, valence electrons increase progressively across a period, determining chemical properties.}$$

$$\text{The relative atomic mass is calculated by weighted average: } (0.9 \times 6.9) + (0.1 \times 7.1) = 6.9.$$

$$\text{Protons are equal to the atomic number, so this isotope has 15 protons.}$$

$$\text{Van der Waals forces hold iodine molecules in a lattice, allowing them to form solid structures with weak attractions.}$$

$$\text{X-ray diffraction helps study crystal structures by measuring diffraction patterns of X-rays through the lattice.}$$

$$\text{Based on the solubility curve, cooling results in crystallization of solute. The deposited amount corresponds to } 0.20 \, \text{mol.}$$

$$\text{Sodium aluminate causes coagulation by aggregating suspended particles in water, enabling easier filtration.}$$

$$\text{Element X (magnesium) and element Y (chlorine) form an ionic bond, as X donates electrons to Y.}$$

$$\text{Hard water is caused by calcium and magnesium ions, particularly as carbonates and sulfates.}$$

$$\text{Nonpolar solvents like benzene dissolve iodine and naphthalene effectively due to similar intermolecular forces.}$$

$$\text{Argon is the third most abundant gas in the atmosphere after nitrogen and oxygen, contributing about 1\%.}$$

$$\text{Endothermic reactions favor product formation at higher temperatures, shifting the equilibrium to the right.}$$

$$\text{CH}_3\text{COO}^- \text{ is the conjugate base of acetic acid (CH}_3\text{COOH) \text{ in the reaction.}$$

$$\text{Butane has two isomers: n-butane (straight chain) and isobutane (branched chain).}$$

$$\text{This is an esterification reaction where an acid reacts with an alcohol to form an ester and water.}$$

$$\text{The compound contains an alkene and a chloro-group as functional groups.}$$

$$\text{This fermentation reaction produces ethanol and carbon dioxide, commonly used in the beverage industry.}$$

$$\text{Water is necessary for the bleaching action of chlorine gas, as it forms hypochlorous acid, which acts as the bleaching agent.}$$

$$\text{In the laboratory, dried oxygen is collected over mercury to prevent contamination by water.}$$

$$\text{Concentrated H}_2\text{SO}_4 \text{ is a dehydrating agent, which removes water during HNO}_3 \text{ preparation.}$$

$$\text{Bronze is an alloy that is stronger and more durable than pure copper, making it ideal for medals.}$$

$$\text{Baking powder contains NaHCO}_3 \text{, which releases carbon dioxide when heated, causing dough to rise.}$$

$$\text{CH}_3\text{-C} \equiv \text{CH} \text{ (ethyne) is used as a gaseous fuel due to its high energy release during combustion.}$$

$$\text{Catenation is the ability of carbon atoms to bond with one another to form long chains and complex structures.}$$

$$\text{C}_2\text{H}_4 \text{ (ethene) undergoes polymerization to form polyethylene, a widely used plastic.}$$

$$\text{Geometric isomerism occurs in compounds with restricted rotation around a double bond, resulting in different spatial arrangements.}$$

$$\text{The molar mass of CH}_2\text{O \text{ is 30. Molecular formula} = \text{empirical formula} \times 1.5 = \text{C}_3\text{H}_6\text{O}_3.}$$

$$\text{This fermentation reaction is used to produce ethanol, commonly used in alcoholic beverages and fuels.}$$

$$\text{C}_4\text{H}_{10} \text{ has two structural isomers: n-butane and isobutane, differing in their connectivity.}$$

$$\text{This is an esterification reaction where an acid reacts with an alcohol to form an ester and water.}$$

$$\text{Primary amines have one alkyl group attached to the nitrogen atom. Option B fits this description.}$$

$$\text{Aldehydes (alkanals) react with Fehling’s solution, forming a brick red precipitate. Alkanones do not.}$$

$$\text{Both are alkanes and share similar chemical properties as members of the same homologous series.}$$