(a) If the moment of force is assigned a negative sign, then will the turning tendency of the force be clockwise or anti-clockwise?

(b) Complete the following nuclear reactions given below

I. $^{238}_{92}\text{P} \overset{\alpha} \longrightarrow \text{Q} \overset{\beta} \longrightarrow \text{R} \overset{\beta} \longrightarrow \text{S}$

II. $^{A}${Z}\text{X} \overset{\alpha} \longrightarrow \text{X}{1} \overset{\gamma} \longrightarrow \text{X}{2} \overset{2\beta} \longrightarrow \text{X}{3}

(a) If the moment of force is assigned a negative sign, then the turning tendency of the force will be in clockwise direction.

(b)

I. When there is an α emission from $^{238}${92}\text{P} , then the atomic number decreases by 2 and mass number decreases by 4. Hence, we get $^{234}{90}\text{Q}$ .

Now, when $^{234}${90}\text{Q} undergoes β emission, the atomic number increases by 1 and the mass number is unchanged. Hence, we get $^{234}{91}\text{R}$.

In the final step when $^{234}${91}\text{R} undergoes β emission again the atomic number increases by 1 and the mass number is unchanged. Hence we get $^{234}{92}\text{S}$.

So the complete nuclear change is as follows —

$^{238}${92}\text{P} \overset{\alpha} \longrightarrow \space ^{234}{90}\text{Q} \overset{\beta} \longrightarrow \space ^{234}{91}\text{R} \overset{\beta} \longrightarrow \space ^{234}{92}\text{S}

II. When there is an α emission from $^{A}${Z}\text{X} , then the atomic number decreases by 2 and mass number decreases by 4. Hence, we get $^{A - 4}{Z - 2}\text{X}_{1}$

After the γ emission, there is no change in atomic number and mass number. Hence, we get $^{A - 4}${Z - 2}\text{X}{2}

In the final step when there are two β emissions, the atomic number increases by 2 and the mass number is unchanged and we get $^{A - 4}${Z}\text{X}{3}

Hence, the nuclear change is as follows —

$^{A}${Z}\text{X} \overset{\alpha} \longrightarrow ^{A - 4}{Z - 2}\text{X}{1} \overset{\gamma} \longrightarrow ^{A - 4}{Z - 2}\text{X}_{2} \overset{2\beta} \longrightarrow _{\space \space \space \space \space Z}^{A - 4}\text{X}_{3}