## Chemistry: Principles and Practice (3rd Edition)

(a) 9.65 x 10$^4$ J/C (b) 3.00 g/cm$^3$ (c) 6 x 10$^{-2}$ mL (d) 6.6 x 10$^{-34}$ kg
(a) To reduce the number 96,485 J/C to three significant figures, we look at the first three significant figures: 9, 6, and 4. Definitely, we will use the 9 and 6. As for the 4, it will be an estimate, so we look at the digit after it and see that it is an 8; therefore, we will round the number 4 up to 5. To express this number better, we can represent it with scientific notation using the three significant digits to get 9.65 x 10$^4$ J/C. (b) To reduce the number 2.9979 g/cm$^3$ to three significant figures, we look at the first three significant figures: 2, 9, and 9. We will need to round the 2.99 up because the digit following the 9 is a 7, which means we need to round this number up to 3.00 g/cm$^3$. (c) To reduce the number 0.0597 mL to one significant figure, we look at the first three significant figure: the 5. We will need to round the 0.05 up because the digit following the 5 is a 9, which means we need to round this number up to 0.06. We can use scientific notation to write this number in an easier form to digest, so we get 6 x 10$^{-2}$ mL. (d) 6.6 x 10$^{-34}$ kg To reduce the number 6.626 x 10$^{-34}$ kg to two significant figures, we look at the first two significant figures: 6 and 6. We will need to truncate the 6.6 because the digit following the 6 is a 2, which means we need to round this number to 6.6 x 10$^{-34}$ kg.