Chemistry 2011 Jamb Examination

Since ΔH is positive, the forward reaction (N₂O₄ → 2NO₂) is endothermic. Increasing temperature favors endothermic reactions, so the equilibrium shifts to the right, producing more NO₂. This also increases the equilibrium constant because more products are formed at higher temperatures.

Solid iodine consists of I₂ molecules arranged in a lattice. The molecules themselves are held together by weak intermolecular forces known as van der Waal's forces. These forces account for iodine's relatively low melting point and ability to sublime easily.

The arrangement of particles in a crystal lattice is studied using X-ray diffraction. X-rays have wavelengths comparable to interatomic distances, allowing them to diffract through the lattice and produce patterns that reveal the structure.

From the solubility curve, note the solubility at 55°C and 40°C. The difference in solubility corresponds to the amount of solute that crystallizes when the solution is cooled. For 200 cm³ of solution, this difference equals 0.20 mole.
Thus, 0.20 mole of solute is deposited upon cooling.

Sodium aluminate (III) is added during water treatment because it hydrolyzes to form aluminium hydroxide. This hydroxide acts as a flocculant, binding fine suspended particles together into larger aggregates that can be filtered or settled easily. This process is called coagulation, and it helps to clarify water by removing impurities.

First, calculate molar mass of NaOH: \(23 + 16 + 1 = 40 \; g mol^{-1}\).

Number of moles in 2 g is:\[ n = \dfrac{2}{40} = 0.05 \; mol \] Convert volume: \(100 cm^3 = 0.1 dm^3\).

Concentration is:\[ C = \dfrac{0.05}{0.1} = 0.50 \; mol \, dm^{-3} \]

In kinetic theory diagrams, the ideal gas behavior is represented by the curve that follows Boyle’s law exactly without deviation. This is shown by N in the given diagram, representing an ideal case.

Across a period, the number of valence electrons increases progressively as atomic number increases. Non-metallic character generally increases across a period. Elements in the same group share the same number of valence electrons, not shells. Therefore, the correct statement is that valence electrons increase across a period.

Lithium exists as isotopes \(^6Li\) and \(^7Li\).
Relative atomic mass is calculated as weighted average:\[ Ar = (0.9 \times 6) + (0.1 \times 7) \]\[ Ar = 5.4 + 0.7 = 6.1 \] This rounds close to 6.2.

The structure represented allows for two possible distinct arrangements that satisfy valency without violating bonding rules. Therefore, two isomers exist.