JAMB UTME - Chemistry - 2008
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In countries where the temperature falls below 273K, salt is always sprinkled on the icy road in order to
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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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Reduction of nitroalkanes, nitrites and amides is a route for the preparation of
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NH3(g) + HCl(s) → NH4Cl(s)
The entropy change in the system above is
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Detergents are manufactured with straight hydrocarbon chains so as to make them
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Swali 9 Ripoti
The IUPAC nomenclature for the structure above is
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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]
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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
Swali 12 Ripoti
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.
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In the periodic table, the electrical and thermal conductivities are properties of elements that
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The oxidation state of carbon in HCOOH is
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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
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The uncovered raw food that is sold along major roads is likely to contain some amounts of
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If the silver mirror test is positive, it indicates the presence of an
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In recharging a lead-acid accumulator, the reaction at the cathode can be represented as
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Diffusion is slowest in solid particles than in particles of liquid and gases because
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The product obtained when a mixture of benzene vapour and hydrogen are passed over nickel catalyst at 180oC is
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Use the diagram to answer this question.
The gas that can be used to demonstrate the experiment is
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Swali 24 Ripoti
300 cm3 of gas has a pressure of 800 mmHg. If the pressure is reduced to 650 mmHg, find its volume
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P1V1= P2V2
800 * 300 = 650 * V2
V2 = (800 * 300)/650 = 369.23 cm3
Swali 27 Ripoti
When a few drops of water is added to a blue anhydrous cobalt (II) chloride, the colour changes to
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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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The rate of a reaction usually decrease in the concentration of reactants because
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Swali 30 Ripoti
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
Maelezo ya Majibu
HCl + NaOH → NaCl + H2O
CAVA = NA/NB = (0.05 * 32)/(CB * 25)
∴ CB = (0.05 * 32)/25 = 0.064 mol dm-3
Swali 31 Ripoti
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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
Swali 32 Ripoti
If glucose is heated with concentration tetraoxosulphate (VI) acid, it will be dehydrated to
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Swali 33 Ripoti
The experiment that showed that atoms have tiny positively charged nucleus was first carried out by
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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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Swali 36 Ripoti
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]
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Relative molecular mass of NaCl = 23 + 35.5 = 55.5 g/mol
No. of mole of NaCl = 117/55.5 = 2.1 mol
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Reduction of alkanonoes with LialH4 produces
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Which of the following compounds of trioxonitrate (V) will decomposes to give dinitrogen (i) oxide and water when heated?
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Use the diagram to answer this question.
The colour of the fountain water is
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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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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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Swali 45 Ripoti
A hydrocarbon X with a molar mass of 26 consists of 92.3% carbon. What is its molecular formular
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% 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
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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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Swali 48 Ripoti
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]
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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
