Chemistry 2016 Jamb Examination

The given structure shows the presence of an \( \text{OH} \) group (hydroxyl group) attached to one of the carbon atoms and \( \text{Cl} \) atoms (chloro substituents) on the terminal and another carbon atom.

There are no carbon–carbon double bonds, so it is not an alkene.

Hence, the compound contains hydroxyl and chloro functional groups.

In an energy profile diagram, the curve shows the progress of a reaction against the energy change.

The highest point on the curve represents the activated complex, while the energy difference between the reactants and this highest point is called the activation energy (X).\[ E_a = E_{\text{activated complex}} - E_{\text{reactants}} \] Hence, X is the activation energy.

In the potential energy diagram, the products have lower potential energy than the reactants. This means energy is released to the surroundings.

The difference in energy between reactants and products represents the enthalpy change (\( \Delta H \)), which is negative for exothermic reactions:
\[ \Delta H = E_{\text{products}} - E_{\text{reactants}} < 0 \]
Hence, the diagram represents an exothermic reaction.

The titration curve starts at a very low pH (indicating a strong acid) and ends at a high pH (indicating a strong base).

The steep and nearly vertical jump around the equivalence point at pH 7 is characteristic of strong acid–strong base titrations.
\[ \text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O} \]
Thus, the curve represents titration between a strong acid and strong base.

An ideal gas obeys Boyle’s law perfectly, which states that \( PV = \text{constant} \).

This relationship produces a smooth rectangular hyperbola when \( P \) is plotted against \( V \).

Among the curves shown, L represents the ideal gas because it shows a perfect hyperbolic relationship between \( P \) and \( V \).

Hence, the ideal gas is represented by L.

The reaction between methane and chlorine occurs through a free radical substitution mechanism initiated by light energy (photochemical reaction).

The UV light provides the energy to dissociate \( \text{Cl}_2 \) molecules into chlorine radicals:
\[ \text{Cl}_2 \xrightarrow{hv} 2\text{Cl} \cdot \]
Hence, light is the major factor influencing the rate of this reaction.

The reaction is endothermic since \( \Delta H = +\text{ve} \).

According to Le Chatelier’s principle, increasing temperature favors the endothermic direction (forward reaction).

This increases the concentration of \( \text{NO}_2 \) and raises the equilibrium constant \( K \):
\[ \text{N}_2\text{O}_4 (aq) \rightleftharpoons 2\text{NO}_2 (g) \]\[ \text{Forward reaction is endothermic.} \]
Therefore, an increase in temperature will increase the value of the equilibrium constant.

The balanced redox reaction between permanganate ion and iron(II) in acidic medium is:
MnO₄^- + 8H⁺ + 5Fe²⁺ → Mn²⁺ + 5Fe³⁺ + 4H₂O
Hence, Y = 8H⁺(aq).

Geometric (cis–trans) isomerism occurs due to restricted rotation around a double bond or ring structure with different substituents on each carbon. Since the compound in question meets this condition, it exhibits geometric isomerism.

When monosaccharides combine to form polysaccharides, they undergo polymerization by the condensation process, releasing water molecules:
\[ n\, \text{C}_6\text{H}_{12}\text{O}_6 \rightarrow (\text{C}_6\text{H}_{10}\text{O}_5)_n + n\,\text{H}_2\text{O} \]Therefore, P = Polymerization and Q = Condensation.