Significant figures are as follows:
zero before (0.12 = 3 sig fig)
zero trapped (1.02 = 3 sig figs, or 0.012 = 3 sig figs)
zero on the end for whole number (120 = 2 sig figs)
zero on the end for decimal (1.20 = 3 sig figs)
Here are the first couple of answers:
1. 3
7. 2
13. 2
2. 2
8. 4