Chemistry 2008 Jamb Examination
Chemistry 2008 Jamb Examination
Question 31
Which of the following compounds of trioxonitrate (V) will decompose to give dinitrogen (I) oxide and water when heated?
On heating, \( NH_4NO_3 \) decomposes to form \( N_2O \) and \( H_2O \).
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Question 32
When a solution of ammonium trioxocarbonate (IV) is added to a solution of an unknown salt, a white precipitate which is soluble in dilute hydrochloric acid but insoluble in ethanoic acid is formed. This indicates the presence of
The white precipitate soluble in dilute HCl but not in ethanoic acid indicates \( Ca^{2+} \) ions.
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Question 33
Lead is used for making bullets and lead shots because of its
Lead is very dense, making it suitable for bullets and lead shots.
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Question 34
Which of the following gives a precipitate when treated with \( NaOH \) solution?
\( AlCl_3 \) reacts with \( NaOH \) to form a white precipitate of \( Al(OH)_3 \).
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Question 35
The most common ores of iron include
The common ores of iron are magnetite, haematite, and limonite.
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Question 36
The type of isomerism shown by cis- and trans- isomers is
Cis- and trans- isomers arise due to restricted rotation around a double bond, which is a form of geometrical isomerism.
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Question 37
If the silver mirror test is positive, it indicates the presence of an
The silver mirror test (Tollens' test) is used to detect aldehydes (alkanals).
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Question 38
If glucose is heated with concentrated tetraoxosulphate (VI) acid, it will be dehydrated to
Concentrated \( H_2SO_4 \) dehydrates glucose, leaving behind carbon as a residue.
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Question 39
The IUPAC nomenclature for the structure above is
The correct structure corresponds to 2, 3 - dichloro - 4, 4 - dimethyl hex - 2 - ene based on IUPAC nomenclature rules.
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Question 40
A hydrocarbon X with a molar mass of 26 consists of 92.3% carbon. What is its molecular formula?
Mass of C = 92.3 g, Mass of H = 7.7 g (per 100 g).\[ \text{Moles of C} = \dfrac{92.3}{12} \approx 7.69, \]\[\quad \text{Moles of H} = \dfrac{7.7}{1} = 7.7 \]\[ \text{Ratio C:H} \approx 1:1 \]\[ \text{Empirical formula} = CH, \;\]\[ \text{Molar mass} = 13 \]\[ \dfrac{26}{13} = 2 \; \]\[\Rightarrow \; \text{Molecular formula} = C_2H_2 \]