Question

The nuclide X undergoes $\alpha -decay$ and another nuclides Y undergoes ${{\beta }^{-}}-decay$, which of the following statements is/are correct?
A) The $\beta -particles$ emitted by Y may have widely different speeds
B) The $\alpha -particles$ emitted by X may have widely different speeds
C) The $\alpha -particles$ emitted by X will have almost same speed
D) The $\beta -particles$ emitted by Y will have the same speed

Answer 1

An alpha decay is generally a single process and can emit alpha particles as such that the speed remains the same. In beta decay, three processes are involved including capturing off electrons, and may eject beta particles at speed of light. This speed might get altered because of different processes.

Complete step-by-step answer: Nuclide X undergoes $\alpha -decay$ and another nuclides Y undergoes ${{\beta }^{-}}-decay$
Alpha decay or as we known it as $\alpha -decay$ is type of radioactive decay in which atomic nucleus emits an alpha particle helium nucleus along with transform with 'decays' into different atomic nucleus with mass number that are reduced by four with an atomic number that is reduced by two. Alpha particles which are having a typical kinetic energy of the $5\text{ }MeV$ and having a speed of about $15,000,000m/s$ align with the $5$ of speed of light. There is surprisingly a very small variation around this due to energy with the heavier dependence being half-life of the process on that energy produced. Due to small variation in kinetic energy alpha particles have almost the same speed.
In nuclear physics beta decay is a type of radioactive decay in which a beta particle i.e. fast energetic electron or positron is emitted from an atomic nucleus transforming the original nuclide to isobar. Beta particles having mass which is half one thousandth of a mass of proton along with a carry either single negative that are electron or positive which are positron charge. As they have small mass and can be released with high energies they can reach relativistic speeds that are close to the speed of light. A maximum of three processes take place meanwhile during beta decay along with this change speed of emission of both particles substantially hence they emit at widely different speeds.
So another correct answer is A and C i.e. the $\beta -particles$ emitted by Y may have widely different speeds and the $\alpha -particles$ emitted by X will have almost the same speed.

Hence, one of the correct answers is C).

Note: An in-depth knowledge of alpha and beta decay is required to solve such questions. Learn about the different types of alpha and beta decays, the elements that can undergoes these decays and how the alpha or beta particle is emitted during such decay reactions. This will give an insight on how and at what speed these particles are emitted.