Per NCERT, the AVERAGE ATOMIC MASS of carbon is shown in the periodic table as approximately 12.011 u — even though ¹²C has mass exactly 12.000 u. Why?
ABecause the periodic table is wrong
BBecause of rounding error
CBecause natural carbon contains ¹²C (98.892%) AND ¹³C (1.108%) — the weighted average is slightly above 12
DBecause carbon expands when measured
Answer & Solution
Correct answer: C. Because natural carbon contains ¹²C (98.892%) AND ¹³C (1.108%) — the weighted average is slightly above 12
Per NCERT §1.7.2 example, average atomic mass of C ≈ 12.011 due to ¹²C + ¹³C natural mixture.
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