JAMB Past Questions and Answers - Page 1573

7,861.

A metallic ion X2+ with an inert gas structure contains 18 electrons. How many protons are there in this ion?

A.

20

B.

18

C.

16

D.

2

Correct answer is A

No explanation has been provided for this answer.

7,863.

An increase in temperature causes an increase in the pressure of a gas because there is an increase in the?

A.

average velocity of the molecules

B.

number of collisions between the molecules

C.

density of the molecules

D.

free mean path between each molecules and other

Correct answer is B

No explanation has been provided for this answer.

7,864.

One mole of propane is mixed with five moles of oxygen. The mixture is ignited and the propane burns completely. What is the volume of the products at s.t.p?

(G.M.V = 22.4 dm3 mol-1)

A.

112.0 dm3

B.

67.2 dm3

C.

56.0 dm3

D.

44.8 dm3

Correct answer is B

C3H8 + 5O2 → 3CO2 + 4H2O
When the mixture is ignited CO2 is collected as product. From the equation 33 moles of CO2 is produced which equals 3 x 2.4 dm3 = 67.2 dm3 at S.T.P

7,865.

2.25g of a sample of an oxide of copper on reduction gave 2.0g of copper. 2.50g of another oxide of copper on reduction also gave 2.0g of copper. These results are in accordance with the law of?

A.

constant composition

B.

conservation of matter

C.

multiple proportions

D.

definite proportions

Correct answer is C

law of multiple proportions, statement that when two elements combine with each other to form more than one compound, the weights of one element that combine with a fixed weight of the other are in a ratio of small whole numbers.