Chemistry 2024 Jamb Examination
Chemistry 2024 Jamb Examination
Question 111
Calculate the number of moles of Copper that will be deposited, if 2 Faraday of electricity is passed through the copper during the electrolysis of copper(II)tetraoxosulphate(VI)
[1F = 96500C]
[1F = 96500C]
Copper(II) ion, Cu2+, requires 2 moles of electrons to deposit 1 mole of copper: \[Cu^{2+} + 2e^- \rightarrow Cu\]Given 2 Faraday of electricity, number of moles of Cu deposited = \( \dfrac{2}{2} = 1 \) mole. Therefore, 1 mole of copper will be deposited.
Not clear enough?
Question 112
The volume occupied by 1 mole of an ideal gas at a temperature of 130°C and a pressure of 1.58 atm is
[R = 0.082 atm dm3 K−1 mol−1]
[R = 0.082 atm dm3 K−1 mol−1]
Using the ideal gas equation: \[PV = nRT\]\[V = \dfrac{nRT}{P} \]\[= \dfrac{1 \times 0.082 \times (130 + 273)}{1.58} \approx 14.84 \; \text{dm^3}\]Thus, the gas occupies approximately 14.84 dm3.
Not clear enough?
Question 113
If a salt weighs 2g and upon exposure to the atmosphere weighs 1.5g, this is as a result of
Efflorescence occurs when a hydrated salt loses water to the atmosphere and becomes lighter. Here, the salt's mass decreases from 2g to 1.5g due to loss of water, which is characteristic of efflorescent salts.
Not clear enough?
Question 114
The compound of Copper used as a fungicide is
Copper(II) sulfate, CuSO4, is widely used as a fungicide in agriculture to control fungal diseases on plants. Other copper compounds listed are not commonly used as fungicides.
Not clear enough?
Question 115
The percentage of hydrogen in the sixth member of the class of the aliphatic alkanes is [H =1, C =12]
The sixth member of the alkanes is hexane (C6H14).
Percentage of H = \( \dfrac{14 \times 1}{6\times 12 + 14} \times 100 = \dfrac{14}{86} \times 100 \)
\( \approx 16.28\%\)
Thus, the percentage of hydrogen is 16.28%.
Percentage of H = \( \dfrac{14 \times 1}{6\times 12 + 14} \times 100 = \dfrac{14}{86} \times 100 \)
\( \approx 16.28\%\)
Thus, the percentage of hydrogen is 16.28%.
Not clear enough?
Question 116
The law which states that a pure chemical compound, no matter how it is made, will be made up of the same elements contained in the same proportion by mass is
The law of definite proportion states that a given chemical compound always contains the same elements in the same proportion by mass, regardless of its source or method of preparation. This law underlies stoichiometry in chemistry.
Not clear enough?
Question 117
The stability of atomic nucleus is determined by ratio of
Nuclear stability is determined by the neutron-to-proton (n/p) ratio. A proper balance between neutrons and protons provides strong nuclear forces to hold the nucleus together. Too many or too few neutrons compared to protons results in instability.
Not clear enough?
Question 118
25.0g of potassium chloride were dissolved in 80g of distilled water at 30°C. Calculate the solubility of the solute in mol/dm3. [K =39, Cl = 35.5]
Moles of KCl = \( \dfrac{25}{39+35.5} = \dfrac{25}{74.5} \approx 0.3356 \) moles
Volume of water = 80 g ≈ 0.08 dm3 (assuming density ≈ 1 g/cm3)
Solubility = \( \dfrac{0.3356}{0.08} \approx 4.2 \) mol/dm3
Therefore, the solubility is approximately 4.2 mol/dm3.
Volume of water = 80 g ≈ 0.08 dm3 (assuming density ≈ 1 g/cm3)
Solubility = \( \dfrac{0.3356}{0.08} \approx 4.2 \) mol/dm3
Therefore, the solubility is approximately 4.2 mol/dm3.
Not clear enough?
Question 119
An example of a physical change is
Liquefaction of liquids is a physical change because it involves only a change of state without altering the chemical composition. Slaking of lime, dissolution in acid, and rusting are chemical changes.
Not clear enough?
Question 120
The product formed when ethyne is passed through a hot tube containing finely divided iron is
When ethyne passes over heated iron, it undergoes polymerisation due to the catalytic effect of the metal. The product is polymeric in nature, forming long-chain compounds.