Jamb Chemistry Past Questions For Year 1991

Question 6

Which of the following are mixtures?

i, Petroleum

ii, Rubber latex

iii. Vulcanizer's solution

iv, Carbon (II)sulphide

jamb 1991

• A. i, ii and iii
• B. i, ii and iv
• C. i and ii only
• D. i and iv

Question 7

The ions X_- and Y₊ are isoelectronic, each containing a total of 10 electrons.

How many protons are in the nuclei of the neutral atoms of X and Y respectively?

jamb 1991

• A. 10 and 10
• B. 9 and 9
• C. 11 and 9
• D. 9 and 11

Question 8

The electronic configuration of an elements is 1s22s22p63s23p3. How many unpaired electrons are there in the element?

jamb 1991

• A. 5
• B. 4
• C. 3
• D. 2

Question 9

Atoms of element X (with 2 electrons in the outer shell). combine with atoms of Y (with 7 electrons in the outer shell). Which of the following statements is FALSE? The compound formed?

jamb 1991

• A. has formula XY
• B. is likely to be ionic
• C. contains X²⁺ ions
• D. contains Y^- ions

Question 10

A sample of a gas exerts a pressure of 8.2 atm when confined in a 2.93 dm³ container at 20°C. The number of moles of gas in the sample is?

(R = 0.082 litre atm / deg mole)

jamb 1991

• A. 1.00
• B. 2.00
• C. 3.00
• D. 4.00