2024 - JAMB Chemistry Past Questions and Answers - page 8

Water pollutants are substances that contaminate water bodies and make them unsafe for various uses.

A. Inorganic fertilizers: These contain chemicals like nitrates and phosphates that can cause eutrophication, leading to algal blooms and oxygen depletion in water bodies.

B. Warm water affluent: Thermal pollution, like warm water from industrial processes, can reduce the oxygen solubility in water and harm aquatic life.

C. Oxygen gas: Oxygen is essential for aquatic life and is naturally present in water. It is not a pollutant.

D. Biodegradable waste: Although biodegradable waste can deplete oxygen as it decomposes, leading to pollution, it is, by itself, not a pollutant, but the process it initiates can be considered a form of pollution. Therefore, the only substance listed that is not a water pollutant is oxygen gas.

The reaction shows the capture of a neutron by Uranium-238, forming Uranium-239. Uranium-239 is an unstable isotope and will undergo radioactive decay. Therefore, the process produces a radioactive isotope.

• The equation shows the addition of a neutron to the Uranium-238 nucleus.
• This results in a new isotope of Uranium.
• This new isotope is unstable and will undergo radioactive decay.

Carbon(IV) oxide, also known as carbon dioxide (CO₂), has a carbon atom at the center double-bonded to two oxygen atoms, resulting in a linear shape.

The correct answer is the oxy-acetylene flame, used for cutting and welding metals.

Oxy-ethylene flame: Possibly a misunderstanding of oxy-acetylene flame; it produces very high temperatures suitable for cutting and welding metals.

Acetylene flame: Standard term for high-temperature flame for metalwork.

Miners' lamp/Hunters' torch: Do not require high temperatures generated by a gas flame mixed with oxygen.

Permalloy is an alloy primarily composed of iron (Fe) and nickel (Ni).

Alkanoates, also known as esters, are characteristic components of lipids (fats and oils), formed by esterification of fatty acids with glycerol.

Solution steps:

1. Calculate empirical formula mass: C (12 g/mol) + H₃ (3 g/mol) = 15 g/mol
2. Determine ratio: 30 / 15 = 2
3. Multiply subscripts: C: 1×2=2, H:3×2=6 → Molecular formula: C₂H₆

Water glass is a solution of sodium silicate (Na₂SiO₃), also known as sodium trioxosilicate(IV).

C₃H₈O represents alcohols or ethers. Possible isomers:

• CH₃CH₂CH₂OH (propan-1-ol)
• CH₃CH(OH)CH₃ (propan-2-ol)
• CH₃OCH₂CH₃ (methyl ethyl ether)

Considering only alcohols, there are 2 isomers: propan-1-ol and propan-2-ol.

Sulphur(IV) oxide (SO₂) is commonly used as a drying agent due to its ability to absorb moisture from substances.