Answer:
<em><u>spontaneous composition</u></em> is the ingnition
of the substance due to the repid oxidation of its on material.
There is no requirement of heat of external sources.
<em><u>Rapid composition</u></em> on the other hand release large amount of heat and light energy.
Explosion and the firecracker is the best example of Rapid composition.
This is a neutron induced fission, therefore a neutron will be added to the U²³⁵ to cause the reaction, and thus it will be added to the left side. There will be unknown number of neutrons produced and thus we put this on the right hand side.
n₁ + U²³⁵ = Te¹³⁷ + Zr ⁹⁷ + xn1 ( n1 to mean a neutron of mass 1)
To balance the masses on both sides of the equation;
1 + 235 = 137 +97+ x
x = 2
the end reaction will be
n₁ +U²³⁵ = Te¹³⁷ + Zr⁹⁷ + 2 n₁
Mass of sodium :- 23 grams
Mass of Chlorine :- 35.5 grams
Mass of NaCl :- 58.5 grams
mass given :- 25 grams
moles :- 0.432 ( given mass/ ionic mass)

B. Two significant figures
Your final answer can only have as many significant figures as the number that has the least amount of significant figures in it, which is (0.0065)