Question

Write the symbol for the missing reactant.

Answer 1

There is a shortcut trick while doing such fill in the blanks of nuclear reactions of hydrogen and helium

Let a,b,care elements of set N

$\\ \rm\Rrightarrow {}^{a}_1 H+{}^b_1H={}^c_2He\dots$

• Here c must be a+b+1

Now

for our question

• c=4
• a=3

Hence b=4-3+1=1+1=2

So

The missing place should b e deuterium of heavy water

In nuclear reactions energy is released so it's mentioned on product side not reactant side