Question

Which of the following statements is not correct?

0.20 mole of O2= 6.4 g

0.75 mole of H2CO3= 47 g

3.42 moles CO = 95.8 g

4.1 moles Li2O = 94 g

I need help please :/

Answer 1

Well this isn't chemistry here
But still:
http://www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
In here I found that molar mass of Oxygen (O) is about 16g/mol and for Lithium (Li) it is about 7 so the 4th one goes:
\[ Li2O_{g/mol} = Li_{g/mol} + 2 \cdot O_{g/mol} = 7_{g/mol} + 32_{g/mol} = 39_{g/mol} \\
Li2O_{g/mol} \cdot 4.1_{mol} = 39_{g/mol} \cdot 4.1_{mol} = 159.9_g \\
159.9_g \ne 94_g
\]
Hope I got it right =S