Answer:
S1) False. 2³ is 2 × 2 × 2 which is 8, not 6.
S2) False. ( 2x / 3y ^ (2) ) ^ (3) =
( (2x) ^ (3) / ( (3y) ^ (2) ) ^ (3) ) = (2)³ × (x)³ / (3)³ × (y²)³ = 8 × x³ / 27 × y⁶ = 8x³ / 27y⁶.
i.e (a^b)^c = a^(b × c).
S3) True.
S4) True.
S5) False. x^(-3) = 1 / x^(3) ≠ 1 / 3x