Question

What is the number of electrons that would weigh 1 kg? Mass of an electron is $$9.11\times {10}^{(-31)}kg$$.

Answer 1

Hint: The mass of the electron is provided, and the mass which the electrons need to achieve is 1 kilogram. Thus we will use this and multiply the number of electrons with the mass of a single electron to find out the total mass which those particular numbers of electrons are able to achieve which should be equal to 1 kilogram.

Complete step by step answer:
Mass is an intrinsic property, which is a quantitative measure of inertia and is a fundamental property of all kinds of matter or quantity. Mass is measured in a number of units such as gram, kilogram, ton, tone, milligram and many more. Electrons are fundamental particles. It possesses a charge and charge is also a fundamental property of matter as well. Now we are given that the mass of the electron is equal to $$9.11\times {10}^{(-31)}kg$$.

We want to find the number of electrons which are needed to form a mass which is equivalent to 1 kilogram. Thus we will use the below formula to find the number of electrons.
$$M=n{m}_e$$
Here, M is the total mass which is given, n is the number of electrons which are present and $$m_e$$ is the mass of a single electron which is present. Thus, using the given numbers in the question in the given formula, we will have;
$$\begin{gathered} 1kg=n\cdot 9.11\times {10}^{(-31)}kg \\ \Rightarrow n={\displaystyle \frac{1}{9.11\times {10}^{(-31)}}} \\ \therefore n=1.097\times {10}^{(32)} \end{gathered}$$
Thus, the number of electrons which are needed to form 1 kilogram of mass is $$1.097\times {10}^{(32)}$$.

Note:According to the conservation of mass, mass is a fundamental property which can neither be created nor can it be destroyed. The total mass of a system has to be constant. Although, according to modern physics, mass can be converted into energy according to Einstein's famous equation$$E=m{c}^2$$.