Question

how many significant figures are present in 2.020 × 10^(-25) and 5.00 × 10^(27) respectively?
a 4 and 3
b 3 and 4
c 2 and 4
d none of the above

Explanation:

Step1: Recall significant - figures rule

Non - zero digits and zeros between non - zero digits are significant. Trailing zeros after a decimal point are significant.
For the number $2.020\times10^{-25}$, the digits 2, 0, 2, and 0 are significant. So, it has 4 significant figures.

Step2: Analyze the second number

For the number $5.00\times10^{27}$, the digits 5, 0, and 0 are significant. So, it has 3 significant figures.

Answer:

A. 4 and 3