2019 - JAMB Chemistry Past Questions and Answers - page 3
21
When ammonia and hydrogen ion bond together to form ammonium ion, the bond formed is called
A
electrovalent bond
B
co-ordinate bond
C
ionic bond
D
covalent bond
22
Which of the following represents the kind of bonding present in ammonium chloride?
A
ionic only
B
covalent only
C
ionic and dative covalent
D
dative covalent
23
Consider the reaction
A\(_{(s)}\) + 2B\(_{(g)}\) → 2C\(_{(aq)}\) + D\(_{(g)}\)
What will be the effect of a decrease in pressure on the reaction?
A
the equilibrium will shift
B
rate of forward reaction will increase
C
rate of backward reaction will increase
D
rates of forward and backward reaction are not affected
24
For the general equation of the nature
xP + yQ ⇌ mR + nS, the expression for the equilibrium constant is
A
k[P]\(^x\)[Q]\(^y\)
B
\(\frac{m[R][S]}{x[P]y[Q]}\)
C
\(\frac{[P]^x[Q]^y}{[R]^m[S]^n}\)
D
\(\frac{[R]^m[S]^n}{[P]^x[Q]^y}\)
25
Which of the following reactions is an oxidation process?
A
2H\(^+\) + 2e\(^-\) \(\to\) H\(_2\)
B
2O\(^{2-}\) + 4e\(^-\) \(\to\) O\(_2\)
C
OCl\(^-\) + H\(_2\)O + 2e\(^-\) \(\to\) 2OH\(^-\) + Cl\(^-\)
D
Cl + e\(^-\) \(\to\) Cl\(^-\)
26
If acidified Potassium Dichromate(VI) (K\(_2\)Cr\(_2\)O\(_7\)) acts as oxidizing agent, color changes from
A
yellow to green
B
orange to green
C
yellow to red
D
orange to red
27
The heat of formation of ethene, C\(_2\)H\(_4\) is 50 kJmol\(^{-1}\), and that of ethane, C\(_2\)H\(_6\) is -82kJmol\(^{-1}\). Calculate the heat evolved in the process:
C\(_2\)H\(_4\) + H\(_2\) \(\to\) C\(_2\)H\(_6\)
A
-122kJ
B
-132kJ
C
-88kJ
D
-60kJ
28
Which of the following statements about catalyst is false?
A
biological catalysts are called enzymes
B
catalyst do not appear in the balanced equation
C
catalyst reduce the activation energy for a reaction
D
catalysts do not alter the mechanism of the reaction and never appear in the rate low
29
Which of the following does not support the fact that air is a mixture?
A
the constituents of air are in a fixed proportion by mass
B
it cannot be represented with a chemical formula
C
the constituents of air can be separated by physical by physical means
D
none of the above
30
What technique is suitable for separating a binary solution of potassium chloride and potassium trioxochlorate (V)?
A
Fractional crystallization
B
Fractional distillation
C
Filtration
D
Evaporation
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