Question 581:

• 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 582:

• 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 583:

• 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

Question 584:

• JAMB 1989

How many valence electrons are contained in the element represented ³¹₁₅P?

A. 3
B. 5
C. 15
D. 31

Question 585:

• JAMB 1989

The gaseous pollutant sulphur (IV)oxide is most likely to be detected in fairly reasonable quantities in the area around a plant for the

A. Extraction of aluminium from bauxite
B. Production of margarine
C. Smelting of copper
D. Production of chlorine from brine