NEET
- Exam
- NEET
- Subject
- Chemistry
- Chapter
- Some Basic Concepts of Chemistry
NEET · Chemistry · Some Basic Concepts of Chemistry
Given below are two statements; one is labelled as Assertion (A)...
Given below are two statements; one is labelled as Assertion (A) and the other is labelled as Reason(R).
Assertion (A) : The average mass of one atom is 12.011 amu, which is not the actual mass of one atom.
Reason (R) : Three isotopes ({ }^{12} \mathrm{C},{ }^{13} \mathrm{C}) and ({ }^{14} \mathrm{C}), of are found in nature.
In the light of the above statements, choose the most appropriate answer from the options given below :
Options
- AIf (A) & (R) both are correct and (R) is the correct explanation of (A).
- BIf (A) & (R) both are correct but (R) is not the correct explanation of (A).
- C(A) is correct but (R) is incorrect.
- D(A) & (R) both are incorrect.
Correct answer
A. If (A) & (R) both are correct and (R) is the correct explanation of (A).
Step-by-step solution
Assertion (A):
"The average mass of one C atom is 12.011 amu, which is not the actual mass of one C atom."
- This is correct. The average atomic mass (12.011 amu) is a weighted average of the masses of different carbon isotopes, not the mass of any single carbon atom.
Reason (R):
"Three isotopes ({ }^{12} ), and ({ }^{14} ) of carbon are found in nature."
- This is partially correct. While ({ }^{12} ) and ({ }^{13} ) are stable and naturally occurring, ({ }^{14} ) is radioactive and present in trace amounts. However, the statement explains why the average atomic mass is not a whole number.