Review the nuclear reaction: 

${}_{88}R{a}^{226}\stackrel{-\alpha }{\to }Rn\stackrel{-\alpha }{\to }Po\stackrel{-\alpha }{\to }Pb\stackrel{-\beta }{\to }Bi$

Point out the correct statement-

If Uranium (mass number $238$ and atomic number $92$) emits an $\mathrm{\alpha }$-particle, the product has the mass number and atomic number:

(a) $236$ and $92$

(b) $234$ and $90$

(c) $238$ and $90$ 

(d) $236$ and $90$

Potassium-$40$ decays in three different ways:

a very very small amount ($0.001$ per cent) decays directly to ${}_{18}{}^{40}\mathrm{Ar}$ by ${\mathrm{\beta }}^{+}$ emission.

Suggest how this process might be described using a nuclear equation.

Represent the union of two sets by Venn diagram for each of the following.

$X=\{x | x$ is a prime number between $80$ and $100\}$

$Y=\{y | y$ is an odd number between $90$ and $100\}$

Select whether the following statement is True or False:

Electrons are electrically neutral subatomic particles.

In 1930, the physicist Paul Dirac proposed that all the fundamental particles have antiparticles whose electrical properties are opposite to the familiar particles. 

Predict the charge on the antielectron and write its nuclide symbol.

In 1932, the American physicist Carl Anderson (1905-1991) discovered the 'anti-electron' (now called a positron) by allowing cosmic rays to pass through a cloud chamber when particles and anti-particles collide they annihilate each other and are converted into energy.