Answer: a) 
b) 
Explanation:
A nuclear fission reaction is defined as the reaction in which a heavy nucleus splits into small nuclei along with release of energy.
a) The given reaction is 
Now, as the mass on both reactant and product side must be equal:


Thus three neutrons are produced and nuclear equation will be: 
b) For the another fission reaction:

To calculate A:
Total mass on reactant side = total mass on product side
235 + 1 = A + 94 + 2
A = 140
To calculate Z:
Total atomic number on reactant side = total atomic number on product side
92 + 0 = 56 + Z + 0
Z = 36
As Krypton has atomic number of 36,Thus the nuclear equation will be :

The subatomic particles found in the area surrounding the nucleus of an atom are called electrons.
Yes, you're correct. If you put all of them on the K scale, then 0C is at 273, 0F is at 255, and 0K is at zero.