Learn more about the properties, composition, and structure of substances (elements and compounds) with these Chemistry questions and answers. This Test can be used by students preparing for Chemistry in JAMB, WAEC, NECO or Post UTME.
25cm3
10cm3
20cm3
50cm3
Correct answer is D
Equation of reaction : 2NaOH + H2SO4 → Na2SO4 + 2H2O
Concentration of a base, CB = 0.5M
Volume of acid, VA = 10cm3
Concentration of an acid, CA = 1.25M
Volume of base, VB = ?
Recall:
CAVACBVB=nAnB ... (1)
N.B: From the equation,
nAnB=12
From (1)
1.25×100.5×VB=12
12.50.5VB=12
25 = 0.5VB
VB = 50.0 cm3
Cr2O2−7 + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O.
The oxidation number of chromium changes from
+5 to +3
+6 to +3
-2 to +3
+7 to +3
Correct answer is B
Cr2O2−7 + 6Fe2+ + 14H+ → 2Cr3+ + 6Fe3+ + 7H2O
The oxidation of Cr in Cr2O2−7 :
Let the oxidation of Cr = x;
2x + (-2 x 7) = -2 ⟹ 2x - 14 = -2
2x = 12 ; x = +6
Hence, the change in oxidation of Cr = +6 to +3
Which of the following pairs cannot be represented with a chemical formula?
air and bronze
bronze and sodium chloride
copper and sodium chloride
caustic soda and washing soda
Correct answer is A
No explanation has been provided for this answer.
Which of the following describes the chemical property of acids?
None of the above
Acid + XCO3 → Salt + H2O + NH3
Acid + NaOH → Normal salt + CO2
Acid + XnCO3 → Salt + H2O + CO2
Correct answer is D
No explanation has been provided for this answer.
Which of the following pollutants will lead to the depletion of ozone layer?
chlorofluorocarbon
carbon (ii) oxide
hydrogen sulphide
sulphur (iv) oxide
Correct answer is A
No explanation has been provided for this answer.