Stoichiometry - Jamb Chemistry Past Questions and Answers

Question 11:

• JAMB 1980

How many grams of hydrogen gas will be liberated when 6g of magnesium ribbon dissolves in 500cm³ of 6M HCl?
(Mg=24, H=1, Cl=35.5)

A. 1.2 g
B. 0.7 g
C. 0.5 g
D. 0.3 g
E. 0.12 g

Question 12:

• JAMB 1980

20 cm3 of 1 M H\(_2\)SO\(_4\) is mixed 20 cm\(^3\) of 1 M NaOH. The resulting solution is?

A. Acidic with a molarity of 0.50 M H₂SO₄
B. Acidic with a molarity of 0.25 H₂SO₄
C. Neutral
D. Alkaline with a molarity of 0.25 M NaOH
E. Alkaline with a molarity of 0.50 M NaOH

Question 13:

• JAMB 1980

Given the mean atomic mass of chlorine prepared in the laboratory to be 35.5 and assuming that chlorine contains two isotopes of mass number 35 nad 37, what is the percentage composition of the isotope of mass number 35?

A. 20
B. 25
C. 50
D. 75
E. 90

Question 14:

• JAMB 1981

the number of atoms in one mole of a substance is equal to?

A. The atomic number
B. The avogadro number
C. The gas constant
D. The number of neutrons
E. The number of electrons

Question 15:

• JAMB 1981

Na₂CO₃ + 2HCI → 2NaCI + H₂O + CO₂. Using the above equation, what volume of carbondioxide, measured at s.t.p is liberated when 53g of sodium carbonate is dissolved in hydrochloric acid?
(1 mole of gas occupies 22.4 dm³ at s.t.p)
(Na = 23, C = 12, O = 16)

A. 44.8 dm³
B. 11.2 dm³
C. 100.1 dm³
D. 3.0 dm³
E. 22.4 dm³