Paper 1  Objectives  49 Questions
JAMB Exam
Year: 1997
Level: SHS
Time:
Type: Question Paper
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#  Question  Ans 

1. 
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? A. 11% B. 31% C. 35% D. 69%
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Detailed SolutionReaction for the equation:\(2H_{2} + O_{2} \to 2H_{2} O\) \(2 vol : 1 vol : 2 vol\) Hence, 2 volumes of Hydrogen is needed for the reaction with Oxygen to produce steam (water). \(\therefore 12cm^{3} O_{2} \to 2 \times 12cm^{3} = 24cm^{3} H_{2}\) \(\text{Excess of Hydrogen} : 35 cm^{3}  24 cm^{3} = 11 cm^{3}\) \(\text{% Hydrogen left after the reaction} = \frac{11}{35} \times 100% = \frac{220}{7} = 31.48% \) \(\approxeq 31% \) 

2. 
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? A. constant composition B. conservation of mass C. reciprocal proportions D. multiple proportions 
D 
3. 
An element, X, forms a volatile hydride XH_{3} with a vapour density of 17.0. The relative atomic mass of X is? A. 34.0 B. 31.0 C. 20.0 D. 14.0
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Detailed SolutionMolecular Mass = Vapour density x 2 = 17.0 x 2 = 34.0∴ Relative Atomic Mass of X in XH_{3} = 34  3 = 31.0 ∴ x = 31.0 

4. 
A mixture of 0.20 mole of Ar, 0.20 mole of N_{2} and 0.30 mole of He exerts a total pressure of 2.1 atm. The partial pressure of He in the mixture is? A. 0.90 atm B. 0.80 atm C. 0.70 atm D. 0.60 atm
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Detailed SolutionTotal no mole = 0.2 + 0.2 + 0.3 = 0.7Partial pressure of He = (0.3)/(0.7) x 2.1 =0.90 

5. 
The temperature of a body decreases when drops of liquid placed on it evaporate because? A. the atmospheric vapour pressure has a cooling effect on the body B. a temperature gradient exists between the drops of liquid and the body causing the latter to vaporate C. the heat of vapourization is drawn from the body causing it to cool D. the random motion of the liquid molecules causes a cooling effect on the body 
C 
6. 
The electron configuration of two elements with similar chemical properties are represented by? A. 1s^{2}2s^{2}2p^{5} and 1s^{2}2s^{2}2p^{4} B. 1s^{2}2s^{2}2p^{4} and 1s^{2}2s^{2}2p^{6}3s^{1} C. 1s^{2}2s^{2}2p^{6}3s^{1} and 1s^{2}2s^{1} D. 1s^{2}2s^{2}2p^{4} and 1s^{2}2s^{1} 
C 
7. 
In the periodic table, what is the property that decreases along the periodic and increases down the group? A. Atomic number B. Electron affinity C. Ionization potential D. Atomic radius 
D 
8. 
Two elements, P and Q with atomic numbers 11 and 8 respectively , combine chemically to form the compound P_{x}Q_{Y}. The respective values of x and y are? A. 1 and 1 B. 1 and 2 C. 2 and 1 D. 3 and 1 
C 
9. 
Oxygen is a mixture of two isotopes 16O and 18O with relative abundances of 90% and 10% respectively. The relative atomic mass of oxygen is? A. 16.0 B. 16.2 C. 17.0 D. 18.0
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Detailed Solution816O, 818O90% 10% R.A.M = (90)/(100) x 16 + (10)/(100) x 18 = 14.4 + 1.8 = 16.2 

10. 
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? A. 12s B. 14s C. 21s D. 30s
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Detailed Solution(R)_{o}/(R)_{a} √(M)_{a}/(M_{O} (30/7)/(60/t) = √ (35.5)/(16)(60/t) (30/7)/ √(35.5)/(16) t = (60/30)/(7) x (4)√35.5 t = (60 x 7 x √35.5)/(30 x 4) = 21s 
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