Which of the five atoms can be described by the following properties: Relative atomic mass is greater than 30 but less than 40, it has odd atomic number and forms a unipositive ion in solution?

  • A T
  • B W
  • C X
  • D Y
  • E Z
jamb 1978chemistry

The correct answer is D. Y

Y = 19 protons, 19 electrons and 20 neutrons.

Y has electronic configuration 2, 8, 8, 1. Hence, it has one valence electron in the outer shell (Valency of +1).

Mass number = protons + neutrons

= 19 + 20

= 39.

Previous question Next question