Question

Two samples of radium, each of mass $ 1mg $ and $ 0.1mg $ , are taken to study the emission of alpha particles. It will be observed that:
(A) Both samples will emit the same number of alpha particles.
(B) $ 1mg $ of radium will emit 10 times the number of alpha particles per second than $ 0.1mg $ does.
(C) Emission of alpha particles is independent of mass of the samples
(D) $ 0.1mg $ of radium will emit 10 times more than by $ 1mg $ of radium

Answer 1

Hint : It is given that radium on decay gives out alpha particles. Radium consists of 88 protons and has 88 electrons, which gives out radon and alpha particles. We know the mass value of radium used in the process. Find the effect of weight in the alpha particle emission rate.

Complete step by step answer
An alpha particle is defined as a by-product of elements that undergo alpha decay. It is a quick moving product that consists of 2 protons and 2 electrons in the nucleus. Generally, alpha particles are said to be helium gas. They carry a positive +2 charge and have a greater tendency to interact strongly with nearby matter or elements, which can cause rapid reaction. This is the reason why alpha decay is performed in a closed environment and not in open.
Alpha decay is one of the types of radioactive decay processes where the nucleus of the element undergoing decay emits and helium nucleus and hence decays itself to an element with atomic number reduced by the factor of two and mass number of the element reduced by 4. Sometimes the new formed decay element can also be referred to as isotope of the element. In our sample, 226 mass number radium undergoes decay to produce 222 mass number radon and an alpha particle. Now the alpha particles emitted per second depends on the weight of the sample.
In this case it is evident that , sample weighing $ 1mg $ will have a greater emission period than the second sample. Thus, $ 1mg $ will produce 10 times that of the $ 0.1mg $ sample.
Hence, option (B) is the right answer for the given question.

Note
Helium is created as a by-product of radioactive decay. Identified as bright yellow light by Pierre Janssen in France during the solar eclipse in the year 1868, it is found that helium is the second most abundant element in the whole universe. Emission of alpha particles was noted by Rutherford in his model of atom dispersion.