Answer
a) two
b) three
c) two
d) three
Work Step by Step
a) Zeros trailing a non-zero number are insignificant, and the number of significant digits after the decimal is zero. So there are 2 sig figs in 310.
b) Use the concepts above and the fact that zeros preceding the non-zero number after the decimal point are insignificant for a number having zero before the decimal point. So, 0.00310 has three sig figs.
c) Any zero AFTER the first non-zero digit is STILL significant. The zeroes BEFORE the first non-zero digit are insignificant.
d) Using the concepts above, 3.10*10^5 has 3 sig figs.
