To determine which of the options is an irrational number, let's evaluate each one:
A. \(0.333\) - This is a repeating decimal that can be expressed as the fraction \(\frac{1}{3}\). It is a rational number.
B. \(\sqrt{8}\) - This can be simplified to \(2\sqrt{2}\). Since \(\sqrt{2}\) is an irrational number, \(\sqrt{8}\) is also irrational.
C. \(\sqrt{49}\) - This simplifies to \(7\), which is a rational number.
D. \(5/22\) - This is a fraction and can be expressed as a decimal, which is approximately \(0.227\), making it a rational number.
Therefore, the only irrational number from the options provided is:
B. \(\sqrt{8}\)