Chemistry 2009 Jamb Examination
Chemistry 2009 Jamb Examination
Question 11
A compound commonly used for sterilization and preservation of specimens and food is
Ethanol is widely used as a disinfectant and preservative because it effectively kills bacteria, fungi, and some viruses. Its antimicrobial properties make it suitable for sterilizing specimens and preserving food for longer periods.
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Question 12
An organic compound reacted with bromine water to give a colourless solution. The compound is probably an
Both alkenes and alkynes readily decolourize bromine water due to the presence of unsaturated bonds. However, alkynes are more reactive in this context, making them the correct answer when a clear solution forms quickly.
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Question 13
Which of the following hydrocarbons is mainly used as fuel?
Methane $CH_{4}$ is the main component of natural gas and is extensively used as a household and industrial fuel. It burns cleanly, releasing significant energy with minimal pollutants compared to other hydrocarbons.
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Question 14
The type of iron that is best suited for welding, making nails, chains and iron rods is
Wrought iron is malleable and tough, making it ideal for welding, nail making, and forging into rods or chains. Unlike brittle cast iron, wrought iron can be shaped easily without breaking during mechanical processes.
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Question 15
In the electrolytic extraction of aluminum, the function of the molten cryolite is to
Molten cryolite is added during aluminium extraction to lower the very high melting point of $Al_{2}O_{3}$. This reduces energy consumption, making the electrolysis process more efficient while also serving as a solvent medium.
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Question 16
One of the products of the thermal decomposition of sodium trioxonitrate (V) is
When heated, sodium trioxonitrate (V), $NaNO_{3}$, decomposes to yield sodium dioxonitrate (III), $NaNO_{2}$, along with oxygen gas. This thermal reaction is important in chemical processes involving nitrates and oxidation reactions.
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Question 17
A cracking process in petroleum refining can be represented by
Cracking involves breaking larger hydrocarbons into smaller, more useful ones. Heptane can be cracked to form propene $C_{3}H_{6}$ and butane $C_{4}H_{10}$, producing both alkanes and alkenes that are valuable for fuels and chemicals.
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Question 18
Which of the following molecules has two other positional isomers?
The compound $CH_{2}CHBrCH_{2}Br$ (1,2-dibromopropane) has two positional isomers where bromine atoms can occupy different positions along the chain. This structural variability makes it the correct answer compared to the other options.
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Question 19
The gasification of coke is used for the manufacturing of
Coke gasification produces synthesis gas (syngas), which is a mixture of carbon monoxide and hydrogen. Syngas is essential in producing fuels, methanol, and other chemicals, making it a key process in industrial chemistry.
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Question 20
The gas that is most useful in protecting humans against solar radiation is
Ozone in the stratosphere forms the ozone layer, which absorbs ultraviolet (UV) radiation from the sun. By filtering out harmful rays, ozone protects humans and ecosystems from DNA damage and other health risks.
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