JAMB UTME - Chemistry - 2008
Pregunta 1 Informe
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
From the equation above, calculate the mass of sodium hydroxide produced by 2.3g of sodium.
[H = 1, O = 16, Na = 23]
Detalles de la respuesta
2Na(s) + 2H2O(l) → 2NaOH(aq) + H2(g)
Relative molecular mass of NaOH = 23 + 16 + 1 = 40smol-1
2 * 23g of sodium react with water to produce
2 * 40g of NaOH
∴ 2.3g of sodium will react with water to produce
(2.3 * 40 * 2)/(23 * 2) = 4.00g
Pregunta 2 Informe
In recharging a lead-acid accumulator, the reaction at the cathode can be represented as
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Pregunta 3 Informe
When a few drops of water is added to a blue anhydrous cobalt (II) chloride, the colour changes to
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Pregunta 4 Informe
In the periodic table, the electrical and thermal conductivities are properties of elements that
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Pregunta 6 Informe
The type of isomerism shown by cis- and trans- isomers is
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Pregunta 7 Informe
0.05 mol dm-3 HCl is neutralized by 25 cm3 NaOH. If the volume of acid used is 32.00cm3, what is the concentration of the base
Detalles de la respuesta
HCl + NaOH → NaCl + H2O
CAVA = NA/NB = (0.05 * 32)/(CB * 25)
∴ CB = (0.05 * 32)/25 = 0.064 mol dm-3
Pregunta 9 Informe
Diffusion is slowest in solid particles than in particles of liquid and gases because
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Pregunta 10 Informe
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Pregunta 11 Informe
NH3(g) + HCl(s) → NH4Cl(s)
The entropy change in the system above is
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Pregunta 12 Informe
Reduction of nitroalkanes, nitrites and amides is a route for the preparation of
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Pregunta 13 Informe
The atom of an element X is represented as yzX . The basic chemical properties of X depend on the value of
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Pregunta 14 Informe
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
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Pregunta 15 Informe
A hydrocarbon X with a molar mass of 26 consists of 92.3% carbon. What is its molecular formular
Detalles de la respuesta
% of H2 = 100 - 92.3 = 7.7%
mole = 92.3/12 7.7/1
7.1/7.1 7.1/7.1
empirical formula = CH
(CH)n = 26
(12 + 1)n = 26
(13)n = 26
n = 26/13 = 2
molecular formula = C2H2
Pregunta 18 Informe
In countries where the temperature falls below 273K, salt is always sprinkled on the icy road in order to
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Pregunta 19 Informe
The substance that is used in the steel industry for the removal of carbon, sulphur and phosphorus impurities from pig iron is
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Pregunta 20 Informe
The oxidation state of carbon in HCOOH is
Detalles de la respuesta
HCOOH
O.N of H + O.N of C + 2* O.N of oxygen of
H = 0
1 + X + 2X - 2 + 1 = 0
2 + X -4 = 0
X = 4 - 2 = +2
Pregunta 21 Informe
In the course of purifying water for town supply the water is passed through large settlings tanks, containing sodium aluminate (III) to remove
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Pregunta 22 Informe
117.0g of sodium chloride was dissolved in the solubility in 1.0dm3 of distilled water at 25oC. Determine the solubility in mol dm-3 of sodium chloride at that temperature
[Na = 23, Cl = 35.5]
Detalles de la respuesta
Relative molecular mass of NaCl = 23 + 35.5 = 55.5 g/mol
No. of mole of NaCl = 117/55.5 = 2.1 mol
Pregunta 24 Informe
If a given quantity of electricity liberates 0.65g of Zn2+, what amount of Hg2+ would be liberated by the same quantity of current?
[Zn = 65, Hg = 201]
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Pregunta 25 Informe
The product obtained when a mixture of benzene vapour and hydrogen are passed over nickel catalyst at 180oC is
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Pregunta 26 Informe
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The correct answer is 11.
pH = -log(H+) Or 14 - pOH
pOH = -log(0.001)
pOH = 3
pH = 14 - 3 = 11
Pregunta 27 Informe
The rate of a reaction usually decrease in the concentration of reactants because
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Pregunta 29 Informe
Use the diagram to answer this question.
The gas that can be used to demonstrate the experiment is
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Pregunta 30 Informe
If glucose is heated with concentration tetraoxosulphate (VI) acid, it will be dehydrated to
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Pregunta 32 Informe
Detergents are manufactured with straight hydrocarbon chains so as to make them
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Pregunta 33 Informe
The experiment that showed that atoms have tiny positively charged nucleus was first carried out by
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Pregunta 35 Informe
Chlorophyll obtained from given leaves of plant can be shown to be composed of more than one coloured component by the technique of
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Pregunta 37 Informe
The vulcanizer's solution is prepared by dissolving rubber in
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Pregunta 38 Informe
If the silver mirror test is positive, it indicates the presence of an
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Pregunta 39 Informe
The uncovered raw food that is sold along major roads is likely to contain some amounts of
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Pregunta 41 Informe
Leads is used for making bullets and lead shots because of its
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Pregunta 42 Informe
16.8 g of sodium hydrogen trioxocarbonate (IV) is completely decomposed by heat. Calculate the volume of carbon(IV) oxide given off s.t.p
[Na 23, C = 12, O = 16, H = 1, Molar volume of a gas at s.t.p = 22.4 dm3]
Detalles de la respuesta
2NaHCO3(s) → Na2CO3(s) + H2O(l) + CO2
Relative molecular mass of NaHCO3 = 23 +1 + 12 + 16 * 3 = 84smol-1
2 * 84g of NaHCO3 will be liberated 22.4dm3 or CO2 at s.t.p
16.8g of NaHCO3 will libertae (16.8 * 22.4)/(2 * 84) = 2.24 dm3
Pregunta 44 Informe
300 cm3 of gas has a pressure of 800 mmHg. If the pressure is reduced to 650 mmHg, find its volume
Detalles de la respuesta
P1V1= P2V2
800 * 300 = 650 * V2
V2 = (800 * 300)/650 = 369.23 cm3
Pregunta 45 Informe
Insoluble salts can be prepared by
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Two soluble metal salts react with each other to form one soluble salt and one insoluble salt . Lead nitrate solution and sodium chloride solution react to produce solid lead chloride , leaving soluble sodium nitrate in solution. The lead chloride can be recovered by filtration.
Pregunta 46 Informe
Use the diagram to answer this question.
The colour of the fountain water is
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Pregunta 47 Informe
Which of the following compounds of trioxonitrate (V) will decomposes to give dinitrogen (i) oxide and water when heated?
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Pregunta 48 Informe
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