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Chemistry Past Questions

Study and practice Chemistry past questions with answers and detailed explanations. Then test your knowledge using our interactive CBT practice platform and prepare confidently for your upcoming examinations.

49 questions JAMB 2505 WAEC 1623 NECO 168 CUSTOM 10
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Past Questions

49 questions
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Question 1 of 9 49 total questions
Question 21
jamb 1997

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 22
jamb 1997
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 23
jamb 1997
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 24
jamb 1997
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 25
jamb 1997
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 26
jamb 1997
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 27
jamb 1997
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 28
jamb 1997
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 29
jamb 1997

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?

A11%
B31%
C35%
D69%
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