2023 - JAMB Chemistry Past Questions and Answers - page 1

If a reversible reaction is subjected to a decrease in temperature, the position of equilibrium will shift in the direction that absorbs heat. This shift is dictated by Le Chatelier's principle.

In general terms:
- If temperature decreases, the reaction will shift in the endothermic direction (the direction that absorbs heat).
- If temperature increases, the reaction will shift in the exothermic direction (the direction that releases heat).

So, for the given scenario of a decrease in temperature: The position of equilibrium shifts to the left.

This is because shifting to the left corresponds to the endothermic direction, helping to absorb the reduced external heat.

Temporary hardness in water is caused by the presence of bicarbonate ions (HCO₃⁻) which can be removed by boiling. When water is heated, bicarbonate ions decompose to form carbonate ions (CO₃²⁻), water, and carbon dioxide. The carbonate ions are insoluble and can be removed by precipitation.

So, the correct answer is Boiling

The type of salt found in antacid medications that is used to relieve heartburn and indigestion is Magnesium chloride.

Antacids often contain compounds such as magnesium hydroxide (Mg(OH)₂) or magnesium carbonate (MgCO₃), which react with stomach acid to neutralize excess acid and provide relief from heartburn and indigestion.

At room temperature (around 20-25 degrees Celsius) and standard pressure, chlorine gas is in the gaseous state

Therefore, the correct answer is Gas

Water is often referred to as the "universal solvent" because it can dissolve a wide variety of substances due to its polar nature.

Therefore, the correct answer is: Water can dissolve a wide variety of substances due to its polar nature.

The chemical structure of soap and detergent molecules typically consists of a hydrophilic (water-attracting) head and a hydrophobic (water-repelling) tail. This structure allows soap and detergent molecules to interact with both water and oils/greases.

Therefore, the correct answer is Hydrophilic head and hydrophobic tail.

An alkene with six carbon atoms has the chemical formula C₆H₁₂. The general formula for an alkene is CnH2n, where "n" is the number of carbon atoms.

In this case, n = 6, so the formula is C₆H₁₂. Each carbon-carbon double bond (C=C) in an alkene contains one pi (\(\pi\)) bond. Since there are two carbon atoms involved in each double bond, the number of pi bonds is equal to half the number of carbon-carbon double bonds.

For a molecule with 6 carbon atoms, there are 5 carbon-carbon double bonds (C=C). Therefore, the number of pi (\(\pi\)) bonds is 5/2, which is 2.5.

However, since pi bonds cannot exist in fractional amounts, we round down to the nearest whole number. Therefore, an alkene with six carbon atoms has 2 pi (\(\pi\)) bonds.

So, the correct answer is 4.

When a molecule has three bonding pairs and no lone pairs around the central atom, its molecular geometry is Trigonal Planar.

The solubility product constant (Ksp) is used to determine the concentration of a solute in a saturated solution. This means it helps in expressing the equilibrium concentrations of ions in a saturated solution.

In summary, the kinetic theory of gases highlights that the pressure of a gas is primarily caused by the frequent and energetic collisions of gas particles with the walls of the container.

1. Constant Motion: Gas particles are in continuous, random motion. They move in straight lines until they collide with another particle or the walls of the container.

2. Collisions with Container Walls: The pressure exerted by a gas is a result of the countless collisions of gas particles with the walls of the container. Each collision imparts a force on the walls, and the cumulative effect of these collisions leads to the overall pressure exerted by the gas.