From the question;
We are to determine the number of significant figures in
a) 0.00040230g
b) 405,000g
a) For 0.00040230g
Trailling zeros to the right of the decimal point are significant
The digits zeros before 4 are not significant
Therefore, the mass has 5 significant figures
b) For 405,000g
Trailling zeros in a whole number with no decimal point are not significant
Therefore
The mass has 3 significant figures
