The measurement 0.510 grams contains three significant figures. This is determined by the rules of significant figures in scientific measurements.
In this case, the ‘0’ before the decimal point does not count as a significant figure because it only indicates the position of the decimal. The digits ‘5’ and ‘1’ are significant because they are non-zero numbers. The ‘0’ at the end is also significant because it is a trailing zero in a decimal number, which indicates precision in the measurement.
To summarize, the significant figures in this measurement are: ‘5’, ‘1’, and ‘0’, giving a total of three significant figures.