Jamb Chemistry 1989 Past Questions and Answers

Question 6:

• JAMB 1989

What is the partial pressure of hydrogen gas collected
over water at standard atmospheric pressure and 25 ^oC if the saturation vapour pressure of water at saturation vapour pressure of water is 23 mm Hg at that temperature?

A. 737 mm Hg
B. 763 mm Hg
C. 777 mm Hg
D. 783 mm Hg

Question 7:

• JAMB 1989

The atomic radius of Li, Na and K are 1: 33A, 1. 54A and 1. 96A res pectively. Which of the following explaqins this gradation in atomic radius?

A. Electropositivity decreases from Li to Na to K
B. Electronegativity decreases from Li to Na to K
C. The number of the electron shells increases from Li to Na to K
D. The elements are in the same period

Question 8:

• JAMB 1989

Elements X and Y have electronic configurations 1s²2s²2p⁶ and 1s²2s²2p⁶3s²3p¹ respectively. When they combine, the formula of the compound formed is

A. XY
B. YX
C. X₂Y₃
D. Y₂X₃

Question 9:

• JAMB 1989

The atomic number of caesium is 55 and its atomic mass is 133. The nucleus of caesium atom therefore contains

A. 78 protons and 55 elections
B. 55 protons and 78 neutrons
C. 55 neutrons 78 electrons
D. 78 protons and 55 neutrons

Question 10:

• JAMB 1989

Four elements P,Q, R and S have atomic numbers of 4, 10, 12 and 14 respectively . Which of these electrons is a noble gas?

A. P
B. Q
C. R
D. S