Properties of Exponential Function for Roots.
The first one is wrong as 4^1/2 would equal √4 = 2
The second choice is correct.
The third choice is correct because ∛8 = 2 and √4 also = 2
The fourth choice is wrong because √8 = 2√2
The fifth choice is also wrong because 2^1/2 would be √2 while √32 is 2^5
The sixth choice is 3^3/2 which would equal √27 = 3√3 which is correct.