Chemistry 2024 Jamb Examination
Chemistry 2024 Jamb Examination
Question 91
An oxide of nitrogen that can rekindle a glowing splint is
Nitrogen(I)oxide, also known as nitric oxide (NO), can support combustion and rekindle a glowing splint because it reacts with oxygen to form nitrogen dioxide, which supports burning. The other oxides do not have the same reactivity with a glowing splint.
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Question 92
In a chemical reaction, surface area of reactants can affect
The rate of a chemical reaction increases with increasing surface area of solid reactants. In the reaction between solid calcium carbonate (CaCO3) and hydrochloric acid (HCl), breaking the CaCO3 into smaller pieces increases the exposed surface, speeding up the reaction. The other reactions involve soluble or gaseous reactants where surface area has negligible effect.
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Question 93
C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(g)
The above equation represents the combustion of ethene. If 10cm3 of ethene is burnt in 50cm3 of oxygen, what would be the volume of oxygen that would remain at the end of the reaction?
The above equation represents the combustion of ethene. If 10cm3 of ethene is burnt in 50cm3 of oxygen, what would be the volume of oxygen that would remain at the end of the reaction?
From the balanced equation, 1 volume of C2H4 reacts with 3 volumes of O2. Therefore, 10 cm3 of C2H4 will consume 30 cm3 of O2. Initial O2 = 50 cm3, O2 remaining = 50 − 30 = 20 cm3.
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Question 94
The hybridization scheme in ethyne is
In ethyne (C2H2), each carbon atom forms two sigma bonds and has two pi bonds. This requires two hybrid orbitals (sp), leaving two unhybridized p orbitals for pi bonding. Therefore, the hybridization of carbon in ethyne is sp.
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Question 95
An organic compound with general formula RCOR' is an
The general formula RCOR' represents a ketone, where R and R' are alkyl groups. Ketones are also called alkanones. Aldehydes have the formula RCHO, alkanoates are esters, and alkanoic acids are carboxylic acids.
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Question 96
The amount of Faraday required to discharge 4.5 moles of Al3+ is
The number of Faradays (F) required = n × z, where n is moles of ions and z is charge.
For Al3+, z = 3
F = 4.5 × 3 = 13.5 Faradays.
For Al3+, z = 3
F = 4.5 × 3 = 13.5 Faradays.
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Question 97
The reaction between alkanoic acids and alkanols in the presence of an acid catalyst is known as
When an acid reacts with an alcohol in the presence of an acid catalyst, an ester and water are formed. This reaction is called esterification. Saponification is the base-catalysed hydrolysis of esters, dehydration involves removing water, and hydrolysis is breaking compounds with water.
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Question 98
2CxHyO + 5O2 → 4CO2 + 4H2O
CxHyO in the equation is
CxHyO in the equation is
Balancing the reaction:
2 CxHyO + 5 O2 → 4 CO2 + 4 H2O
The ratio suggests x = 2, y = 4, giving formula C2H4O.
2 CxHyO + 5 O2 → 4 CO2 + 4 H2O
The ratio suggests x = 2, y = 4, giving formula C2H4O.
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Question 99
Alkylation of benzene is catalyzed by
Friedel-Crafts alkylation of benzene involves the introduction of an alkyl group using an alkyl halide in the presence of a Lewis acid catalyst. Aluminium chloride (AlCl3) is the commonly used catalyst for this reaction.
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Question 100
Benzene formed nitrobenzene at temperature of 60°C when it reacts with mixture of concentrated trioxonitrate(V) acid and concentrated
Nitration of benzene requires the generation of the nitronium ion (NO2+) using concentrated nitric acid and concentrated sulphuric acid (tetraoxosulphate(VI) acid) as the catalyst. The mixture produces NO2+ which attacks benzene to form nitrobenzene.