Question

Statement 1: The average mass of one $Mg$ atom is $24.305$ amu, which is not the actual mass of one $Mg$ atom.
Statement 2 : Three isotopes, ${ }^{24} Mg ,{ }^{25} Mg$ and ${ }^{26} Mg$ of $Mg$ can be found in nature.

• A. If both Statement $1$ and Statement $2$ are true and the statement $2$ is the correct explanation of the statement $1$
• B. If both Statement $1$ and Statement $2$ are true but statement $2$ is not the correct explanation of the statement $1$
• C. If Statement $1$ is true but Statement $2$ is false
• D. If Statement $1$ is false but Statement $2$ is true

Answer 1

Answer: (A)

The average mass of one $Mg$ atom is $24.305 amu$, which is not the actual mass of one $Mg$ atom.
The actual mass of one Mg atom is either 24 amu or 25 amu or 26 amu.
Three isotopes, ${ }^{24} Mg ,{ }^{25} Mg$ and ${ }^{26} Mg$ of $Mg$ are found in nature. they have different natural abundances. Their average mass comes to be $24.305 amu$.
Thus, both Assertion and Reason are correct and Reason is the correct explanation for Assertion.