Question

The number of significant figures in $3400$ is:

A. 4

B. 1

C. 3

D. 2

Answer 1

Significant figures are the numbers which possess valuable positional values. There are four rules which govern the significant rules. This is useful in estimating and rounding off the values to their nearest significant figures. However these are only approximate.

Complete step by step answer

The common rules which are used in the identification of the significant numbers are as follows:

1. Any number which is not equal to zero or which is non-zero is considered as significant.

2. If zeros appear between two non-zero numbers, then that zero is significant.

3. Zeroes which appear to the left of significant numbers are not significant.

4. Zeroes which appear to the right of a significant number may or may not be significant depending on their precision.

The number of significant figures in $3400$, according to rule 4, the number of significant figures is either $\text{4 or 2}$ and clearly not $\text{1 or 3}$. Now since $3400$ is a whole number we can say that it has two significant figures, as the zeros in the left don’t have any value and can be expressed as $3400=34\times 10^{2}=3.4\times 10^{3}$, still we get two significant figures. Thus the number of significant figures in $3400$ has two significant figures as it is a whole number.

Hence, option (D) is correct.

Note:

The numbers on the left have the highest exponential value and hence are the most significant numbers and the numbers to the right have the least exponential value and hence are the lowest significant numbers. Hence to avoid ambiguity, we can use the scientific notation to identify the number of significant figures.