Final answer:
The number 18.34 cm has four significant digits, 150 cm has three, 9.02603 cm has six, and 20.2 cm has three. Zeros at the beginning of numbers are not significant, while zeros between non-zero digits and at the end after a decimal are significant.
Step-by-step explanation:
Identifying the number of significant digits in a number is important for maintaining precision in scientific measurements. Each number given has a certain number of significant digits:
- The number 18.34 cm has four significant digits, which makes the answer to the first question (a) 4.
- The number 150 cm, assuming that the zeros are not placekeepers and are instead measured values, has three significant digits; thus, the second question's answer is (c) 3. However, if the context does not specify that the zeros are measured, this number could be considered to have only one significant digit.
- For the number 9.02603 cm, there are six digits in total, and all of them are significant, making the answer (d) 6.
- Lastly, the number 20.2 cm has three significant digits because zeros after the decimal are significant, corresponding to answer (e) 3.
When determining significant digits, zeros at the beginning of a number are not counted, but zeros between non-zero digits and at the end of a number after a decimal point are. For whole numbers, zeros at the end might be significant depending on additional context or if expressed in scientific notation.