Question

An element E contains 19protons and 20 neutrons the ion formed by E during the formation a stable compound is
(1) E2+ (2) E+ (3) E-(4) E2-

Answer 1

The element is Potassium.
Since it has 19 protons, it has 19 electrons too.
The electrons are arranged as:
 2 in first shell
 8 in second shell
 8 in third shell
 And only one in fourth shell.
To achieve noble gas configuration, it will donate a electron and acquire a positive charge. So answer is E+.

Note: It has nothing to do with no. of neutron.

Answer 2

the element is pottasium

it has 19 electrons and 19 protons

any atom loses or gains electron to get stable electronic configuration of nearest noble element.

argon is the nearest to pottasium so it can lose an electron(argon has 18 electrons)

the ans is (2)