Answer:
0.2
Explanation:
1. First, figure out the molar mass of said element(s).
The molar mass of carbon is 12.0107. Whether you round this or leave it as is depends on your's and/or your teacher's personal preference.
2. Next, convert grams to moles by dividing the initial mass of carbon by the molar mass. Round if neccecary.
2.4g ÷ 12.0107g/mol = 0.2mol