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What is the voltage of the cell represented at Zn(s)/ Zn\(^{2+}\)(aq) //Cu\(^{2+}\)(aq) /Cu(s) given that for Cu\(^{2+}\)(aq)/ Cu (s) E\(^0\) = 0.337V and for Zn\(^{2+}\)(aq) /Zn(s)' E\(^0\) = - 0.763V?
A+0.426V
B-0.426V
C-0.337V
D-1.10V
E+1.10V
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Question 2
waec1989
The oxidation number of chlorine is + 1 in
AKCIO 3
BCI 2O 7
CZnCI2
DHCI
ENaCIO
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Question 3
waec1989
50cm\(^3\) of a saturated solution of potassium trioxonitrate (V)at 40°C contains 5.05g of the salt. What is the solubility of potassium trioxonitrate (V) at 40°C? (KNO\(_3\) = 101)
A1.0 mol dm-3
B1.5 mol dm-3
C2.0 mol dm-3
D2.5mol dm-3
E5.0mol dm-3
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Question 4
waec1989
Which of the following is a condition for a spontaneous reaction?
A∆H -T is zero
B∆H-T∆ S is positive
C∆H-T∆ S is negative
D∆S is zero
E∆S is positive
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Question 5
waec1989
The electronic configuration of two atoms X and Y are as follows: X - 1s 2 2s 22p 63s 1, Y -1s 22s 22p 63s23p 64s 2 which of the statements below is true of the position of X and Y in the Periodic Table?
Ax belongs to group 1, Y belongs to period 2,
Bx belongs to group 1, Y belongs to period 4
Cx belongs to group 2, Y belongs to period 1
Dx belongs to group 3, Y belongs to period 2
Ex belongs to group 3, Y belongs to period 4
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Question 6
waec1989
What quantity of copper will be deposited by the same quantity of electricity that deposited 9.0g of aluminum? (A = 27, Cu = 64)
A64g
B32g
C7.1g
D6.4g
E3.2g
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Question 7
waec1989
Which of the following statements is not true of tin? it
Ais a p-block element
Bis extracted from cassiterite SnO 2
Cis used for protecting iron containers from corrosion
Dcombines with copper to form the alloy brass
Eshows two oxidation states, + 2 and + 4 in most of its compounds
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Question 8
waec1989
The following are s-block elements except
Alithium
Bmagnesium
Cpotassium
Dcalcium
Ealuminium
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Question 9
waec1989
Given that for the reaction. N2(g) + 3H2(g) ⇌ 2NH3(g) ∆H = -92kJ. What is the enthalpy of formation of ammonia from its elements?
A-46KJ mol -1
B-184KJmol -1
C-92KJmol -1
D184KJmol -1
E+46KJmol -1
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Question 10
waec1989
If sulphur is dissolved in carbon (IV) sulphide and the solution is allowed to evaporate, the allotrope of sulphur formed is
Aplastic sulphur
Bamorphous sulphur
Crhombic sulphur
Dmonoclinc sulphur
Ecolloidal sulphur
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Question 11
waec1989
If sulphur is dissolved in carbon (IV) sulphide and the solution allowed to evaporate the allotrope of sulphur formed is
Aplastic sulphur
Bamorphous sulphur
Crhombic sulphur
Dmonoclinc sulphur
Ecolloidal sulphur
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Question 12
waec1989
Given that 1 mole of carbon -12 weighs 12.0g, how many atoms are there in 24.0g magnesium? (C = 12, Mg = 24, NA = 6.02 x 10 23mol-1)
A1/2 x 6.02 x 10 23
B1 x 6.02 x10 23
C2 x 6.02 x 10 23
D3x 6.02 x 10 23
E4x 6.02 x 10 23
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Question 13
waec1989
Which of the following is used extensively in manufacturing photographic chemicals?
AAluminium chloride
BZinc chloride
CSilver chloride
DMercury (ll) chloride
Elron (ll) chloride
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Question 14
waec1989
Given the following half-cell reaction; 2Cl(aq) → CI2(g) + 2e, how many mole of electrons will be required to produce 1.12dm3 of chlorine gas at s.t.p? (Molar volume of a gas at s.t.p. = 22.4dm 3)
A1.00
B0.40
C0.20
D0.10
E0.01
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Question 15
waec1989
Octane number is highest in petrol containing a high proportion of
Aheptane
Boctane
C2-methylpentane
D2, 4-dimethylpentane
E2,2,4-trimethylpentane
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Question 16
waec1989
The rate of the hydrogen in the reaction Zn(s) + 2HCI (aq) → ZnCI 2(g) + H 2(aq) + H 2(g) can be increased by
Ausing Zinc powder instead of Zinc granules
Busing dilute instead of concentrated hydrochloric acid
Ccooling the container in which the mixture is placed
Dusing an alloy of zinc instead of pure zinc
Eusing hydrogen chloride gas instead of hydrochloric acid solution
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Question 17
waec1989
Why is potassium fluoride added to the electrolyte in the extraction of sodium from fused sodium chloride?
APure sodium chloride does not conduct electricity
BPotassium fluoride prevents the sodium produced from attacking the electrodes
CPotassium fluride increases conductivity
DPotassium fluride reduces the temperature at which sodium chloride fuses
Ethe potassium fluride acts as a catalyst
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Question 18
waec1989
Locally produced soap in which wood ash is used as the base is usually soft because the wood ash contains a lot of
Asodium ions
Bpotassium ions
Clithium ions
Dcalcium ions
Emagnesium ions
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Question 19
waec1989
Copper can best be purified by
Aroasting the impure copper in a blast furnace
Bheating the oxide with coke
Celectrolyzing a copper (ll) salt solution using the impure copper as the anode
Dconverting the impure copper to a trioxonitrate (V)
Ewashing the impure copper with sodium hydroxide solution
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Question 20
waec1989
Which of the following carbohydrates does NOT usually occur in the crystalline form?
