Question

find the value of p,q,r and s

Answer 1

Mass no.= Protons + neutrons.

i) protons 12

Mass number 25

25 = 12 + neutrons

Neutrons = 25-12= 13

Protons = electrons

electrons = 13

ii)protons = electrons

protons = 14

Mass no. = Protons + neutrons

= 14+17

=31

Answer 2

if we talk about elements M is magnesium and N is silicon with;

q=14

p=12

r=12

s=28

but, it is given that M &N are ions so,

p=10

q=11

r=13

s=28

the correct option is D