Let a = 0.2101
And, b = 0.2222….
We observe that the second decimal place a has digit 1 and b has digit 2, therefore, a < b. In the third decimal place a has digit 0. So, if we consider irrational number
x = 0.211011001100011…
We find that,
a < x < b
Hence, x is required irrational number