To determine the number of significant figures in the number 0.000129, we follow the rules for counting significant figures:
1. Non-zero digits are always significant.
2. Any zeros between non-zero digits are significant.
3. Leading zeros are not significant because they are only placeholders.
4. Trailing zeros in a decimal number are significant.
Step-by-step process for 0.000129:
1. The leading zeros (0.000) are not counted as significant figures.
2. The digits 1, 2, and 9 are non-zero and, therefore, significant.
So, in 0.000129, the digits 1, 2, and 9 are significant.
Thus, the correct number of significant figures in 0.000129 is 3.
The correct value from the list is 3.
