X is an element with atomic number 20.
(¡) Is it a metal or non-metal? 
(¡¡)Which of the two X or Mg(with atomic number =12) is more reactive? 
(¡¡¡)What is the valency of X? 

Asked by pdcavita | 29th Nov, 2017, 10:00: PM

Expert Answer:

An element with atomic number 20 is Calcium.
i)   Calcium is a metal.

ii)  Calcium is more reactive than Magnesium. 
      As in case of alkali metals and alkaline earth metals reactivity increases with increase in atomic number.

iii) Valency of Calcium is 2.
     Electronic confugaration: (2,8,8,2)

Answered by Varsha | 30th Nov, 2017, 10:48: AM