JAMB Chemistry Past Questions & Answers - Page 6

Calcium belongs to the alkaline earth metals group in the periodic table. It is located in Group 2 and has two valence electrons.

Hematite (Fe\(_2\)O\(_3\)) is the principal ore of iron and is widely mined for the extraction of iron metal.

In an alkene with six carbon atoms, there are 5 sigma (σ) bonds (single bonds) between the carbon atoms. Additionally, there are 4 pi (\(\pi\)) bonds associated with the double bonds between the carbon atoms.

Rust is a reddish-brown compound that forms on the surface of iron in the presence of oxygen and moisture. Its chemical formula is Fe\(_2\)O\(_3\), indicating the presence of two iron atoms and three oxygen atoms in the compound.

The molar mass of water (H2O) is calculated by adding the atomic masses of its constituent elements: 2 hydrogen atoms (each with a molar mass of approximately 1 g/mol) and 1 oxygen atom (with a molar mass of approximately 16 g/mol). Therefore, the molar mass of water is 2 x 1 g/mol + 1 x 16 g/mol = 18 g/mol.

Esters are organic compounds that have a pleasant, fruity aroma. They are responsible for the characteristic smells of fruits and many other fragrant substances.

The molecular weight of products is not directly related to the rate of a chemical reaction. The factors that affect the reaction rate include concentration of reactants, temperature, presence of catalysts, surface area, and the nature of the reactants and products.

When an acidic solution is diluted by adding more solvent (usually water), the concentration of hydrogen ions (H\(^+\)) decreases. As a result, the pH of the solution increases, making it less acidic

During the electrolysis of aqueous sodium chloride using inert electrodes (such as platinum or carbon), the cations (H\(^+\)) are attracted to the cathode and are reduced to form hydrogen gas (H\(_2\)). The anions (OH\(^-\)) are attracted to the anode and are oxidized to form oxygen gas (O\(_2\)).

Pentane (C5H12) is a straight-chain alkane. Alkanes are hydrocarbons with the general formula CnH2n+2. They are called straight-chain alkanes if all the carbon atoms are connected in a continuous chain without any branches. Butane and Isobutane are both C4H10, but Isobutane has a branched structure, not a straight chain. Cyclopentane (C5H10) is a cycloalkane, not a straight-chain alkane.