Significant figures in a number represent the digits that carry meaning contributing to its precision. This includes all digits except:

• All leading zeros.


• Trailing zeros only when they are merely placeholders to indicate the scale of the number (they must not be significant if there is no decimal point).

Here is the explanation for the significant figures of each number in List I:

(A) 1001 - All the digits in this number are significant because there are no leading or trailing zeros acting as placeholders. Hence, this number has 4 significant figures.

(B) 010.1 - The leading zero is not significant, but the zero between 1 and the decimal point, the 1 itself, and the 1 after the decimal point are all significant. So, this number has 3 significant figures.

(C) 100.100 - Here, the number has zeros which are significant since they are between significant digits or after the decimal point. This makes all the zeros and the 1s significant. Therefore, the number has 6 significant figures.

(D) 0.0010010 - The leading zeros are not significant, but the three zeros within and at the end of the number are significant because they are between significant digits or at the end of the number after the decimal. Therefore, this number has 5 significant figures.

Given List I and List II, the correct matching based on the explanation of significant figures is as follows:

Option A

(A) - II (1001 has 4 significant figures)

(B) - I (010.1 has 3 significant figures)

(C) - IV (100.100 has 6 significant figures)

(D) - III (0.0010010 has 5 significant figures)

Thus, the correct answer is Option A.