Answer:B
Explanation:
For work to be done, the object must move some distance as a result of a force
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 :

In the above case we can say that power given by external agent to pull the rod must be equal to the power dissipated in the form of heat due to magnetic induction.
Part a)
when we pull the rod with constant speed then power required will be product of force and velocity
here we will have

P = 4 W
v = 4 m/s
now we will have


So external force required will be 1 N
PART B)
now in order to find magnetic field strength we can say

here we know that induced EMF in the wire is E = vBL
so power due to induced magnetic field is given by


by solving above equation we will have

*It's nucleas. There are protons, neutrons and electrons.