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Which of the aqueous solutions with the pH values below will liberate hydrogen when it react with magnesium metals?
A13.0
B7.0
C6.5
D3.0
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Question 42
jamb1997
The hydroxyl ion concentrated, (OH-), in a solution of sodium hydroxide of pH 10.0 is?
A10-10 mol dm-3
B10-6 mol dm-3
C10-4 mol dm-3
D10-2 mol dm-3
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Question 43
jamb1997
A saturated solution of AgCl was found to have a concentration of 1.30 x 10-5 mol dm-3. The solubility product of AgCl therefore is?
A1.30 x 10-5 mol2 dm-6
B1.30 x 10-7 mol2 dm-6
C1.69 x 10-10 mol2 dm-6
D2.60 x 10-12 mol2 dm-6
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Question 44
jamb1997
A major process involved in the softening of hard water is the?
Aconversion of a soluble calcium salt to its trioxoncarbonate (lV)
Bdecomposition of calcium trioxocarbonate (lV)
Cconversion of an insoluble calcium salts to its trioxocarbonate (lV)
Doxidation of calcium atoms to its ions
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Question 45
jamb1997
Which of the following gases is the most dangerous pollutant?
AHydrogen sulphide
BCarbon (lV) oxide
CSulphur (lV) oxide
DCarbon (ll) oxide
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Question 46
jamb1997
On recrystallization, 20g of magnesium tetraoxosuphate (IV) forms 41 g of magnesium tetraoxosulphate (IV) crystals, MgSO4. yH2O. The value of y is?
(Mg = 24, S = 32, O = 16, H = 1)
A1
B3
C5
D7
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Question 47
jamb1997
200 cm3 of air was passed over heated copper in a syringe several times to produce copper (II) oxide.
When cooled, the final volume of air recorded was 158cm3. Estimate the percentage of oxygen in the air?
A31%
B27%
C21%
D19%
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Question 48
jamb1997
If 30cm\(^3\) of oxygen diffuses through porous plug in 7s, how long will it take 60 cm\(^3\) of chlorine to diffuse through the same plug?
A12s
B14s
C21s
D30s
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Question 49
jamb1997
Oxygen is a mixture of two isotopes 16-O and 18-O with relative abundances of 90% and 10% respectively. The relative atomic mass of oxygen is?
A16.0
B16.2
C17.0
D18.0
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Question 50
jamb1997
Two elements, P and Q with atomic numbers 11 and 8 respectively , combine chemically to form the compound PxQY. The respective values of x and y are?
A1 and 1
B1 and 2
C2 and 1
D3 and 1
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Question 51
jamb1997
In the periodic table, what is the property that decreases along the periodic and increases down the group?
AAtomic number
BElectron affinity
CIonization potential
DAtomic radius
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Question 52
jamb1997
The electron configuration of two elements with similar chemical properties are represented by?
A1s22s22p5 and 1s22s22p4
B1s22s22p4 and 1s22s22p63s1
C1s22s22p63s1 and 1s22s1
D1s22s22p4 and 1s22s1
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Question 53
jamb1997
The temperature of a body decreases when drops of liquid placed on it evaporate because?
Athe atmospheric vapour pressure has a cooling effect on the body
Ba temperature gradient exists between the drops of liquid and the body causing the latter to vaporate
Cthe heat of vapourization is drawn from the body causing it to cool
Dthe random motion of the liquid molecules causes a cooling effect on the body
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Question 54
jamb1997
A mixture of 0.20 mole of Ar, 0.20 mole of N2 and 0.30 mole of He exerts a total pressure of 2.1 atm. The partial pressure of He in the mixture is?
A0.90 atm
B0.80 atm
C0.70 atm
D0.60 atm
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Question 55
jamb1997
An element, X, forms a volatile hydride XH3 with a vapour density of 17.0. The relative atomic mass of X is?
(H = 1)
A34.0
B31.0
C20.0
D14.0
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Question 56
jamb1997
2.85g of an oxide of copper gave 2.52g of copper on reduction and 1.90g of another oxide gave 1.52g of copper on reduction. The data above illustrates the law of?
Aconstant composition
Bconservation of mass
Creciprocal proportions
Dmultiple proportions
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Question 57
jamb1997
35 cm3 of hydrogen was sparked with 12 cm3 of oxygen at 110°C and 760mm Hg to produce steam. What percentage of the total volume of gas left after the reaction is hydrogen?
