Significant figures include all meaningful digits in a number. Use the rules for counting significant figures carefully, especially for decimals and trailing zeros.
Significant figures represent all the digits in a number that are meaningful in terms of precision. They include all non-zero digits, zeros between non-zero digits, and trailing zeros in decimal numbers. Here is the breakdown:
Thus, 0.00253 (option A), 15.0 (option B), and 163 (option C) all have the same number of significant figures, which is 3.
Therefore, the correct answer is option (4).
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)

Cobalt chloride when dissolved in water forms pink colored complex $X$ which has octahedral geometry. This solution on treating with cone $HCl$ forms deep blue complex, $\underline{Y}$ which has a $\underline{Z}$ geometry $X, Y$ and $Z$, respectively, are
What will be the equilibrium constant of the given reaction carried out in a \(5 \,L\) vessel and having equilibrium amounts of \(A_2\) and \(A\) as \(0.5\) mole and \(2 \times 10^{-6}\) mole respectively?
The reaction : \(A_2 \rightleftharpoons 2A\)