SHA256 hash

Is it difficult to find data that SHA256 hash is 256bits of zero ?

>>4
Technically there are infinitely many strings of data that will generate a zero hash. 2²⁵⁶ is just the number of possible hashes and 2^-256 is the chance of a collision. You could potentially generate well over 2²⁵⁶ strings of data before finding a match.