Chemistry 2004 Jamb Examination
Question 21
An isomer of C5H12 is
The correct option is C. 2-methyl butane.
An isomer of pentane (C₅H₁₂) is 2-methylbutane, which has the same molecular formula but a different structural arrangement. The other options do not have the correct carbon count or structure to be isomers of C₅H₁₂.
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Question 22
Alkanol +Alkanoic acid → Ester +Water
The reverse reaction of the equation above is known as.
The correct option is B. hydrolysis.
The reverse reaction of esterification, where an ester reacts with water to produce an alkanol (alcohol) and an alkanoic acid (carboxylic acid), is known as hydrolysis.
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Question 23
CH3COOH(g) → CH4(g) + CO2(g)
The reaction above is
The correct option is C. decarboxylation.
The reaction involves the removal of a carboxyl group (CO₂) from acetic acid (CH₃COOH) to produce methane (CH₄) and carbon dioxide (CO₂). This process is known as decarboxylation.
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Question 24
A characteristic of the alkane family is
The correct option is A. substitution reaction.
Alkanes primarily undergo substitution reactions, where one or more hydrogen atoms in the molecule are replaced by other atoms or groups of atoms, typically in the presence of a catalyst or under specific conditions.
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Question 25
Pollution of underground water by metal ions is very likely in a soil that has high
The correct option is C. acidity.
Pollution of underground water by metal ions is more likely in soils with high acidity. Acidic conditions can increase the solubility of metal ions, allowing them to leach into groundwater more easily.
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Question 26
The solubility inmol dm-3 of 20g of CuSO4 dissolved in 100g ofwater at 180oC is
[Cu = 64, S =32, O = 16]
The correct option is D. 1.25.
First, calculate the Molar mass of CuSO₄:\[= 64 + 32 + (16 \times 4) = 160 \text{ g/mol}\]
Next, find the number of moles of CuSO₄ in 20 g:\[ = \dfrac{20 \text{ g}}{160 \text{ g/mol}} = 0.125 \text{ moles}\]
Since the solubility is to be expressed in mol/dm³, and 100 g of water is approximately equivalent to 0.1 dm³:\[ \text{Solubility} = \dfrac{0.125 \text{ moles}}{0.1 \text{ dm}^3} = 1.25 \text{ mol/dm}^3\]
Thus, the solubility is 1.25 mol/dm³.
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Question 27
Which of these compounds is a normal salt?
The correct option is A. Na₂CO₃.
Na₂CO₃ (sodium carbonate) is a normal salt because it is formed by the complete neutralization of a strong base (NaOH) with a strong acid (H₂CO₃), with no hydrogen ions left unneutralized. The other options are acidic salts, as they still contain replaceable hydrogen atoms.
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Question 28
A carcinogenic substance is
The correct option is C. asbestos dust.
Asbestos dust is a known carcinogenic substance. Prolonged exposure to asbestos can lead to serious health issues, including lung cancer and asbestosis.
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Question 29
What volume of 0.5moldm-3 H2SO4 will exactly neutralize 20 cm3 of 0.1mol dm3 NaOH solution?
Balanced equation:\[ \quad \mathrm{H_2SO_4 + 2NaOH \rightarrow Na_2SO_4 + 2H_2O}\] Given\[\text{Concentration of NaOH} = 0.1\, \mathrm{mol\,dm^{-3}},\]
\[\quad \text{Volume of NaOH} = 20\, \mathrm{cm^3} = 0.020\, \mathrm{dm^3}\]
\[\text{Moles of NaOH} = 0.1 \times 0.020 = 0.002\, \mathrm{mol}\]
\[\text{From the equation, } 2\, \mathrm{mol\, NaOH}\]
\[\text{ reacts with } 1\, \mathrm{mol\, H_2SO_4}\]
\[\text{Therefore, moles of } \mathrm{H_2SO_4}\]
\[ = \dfrac{0.002}{2} = 0.001\, \mathrm{mol}\]
\[\text{Concentration of } \mathrm{H_2SO_4} = 0.5\, \mathrm{mol\,dm^{-3}}\]
\[\text{Volume of } \mathrm{H_2SO_4}\]
\[= \dfrac{\text{moles}}{\text{concentration}} \]
\[= \dfrac{0.001}{0.5} = 0.002\, \mathrm{dm^3} = 2\, \mathrm{cm^3}\]
\[\boxed{2\, \mathrm{cm^3}}\]
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Question 30
Calcium tetraoxosulphate (V1) dissolves in water only sparingly to form a
The correct option is C. suspension.
Calcium sulfate (CaSO₄) dissolves sparingly in water. When the concentration of dissolved calcium sulfate reaches its solubility limit, any excess will form a suspension of undissolved particles in the water.
