Complex Numbers And Quadratic Equations question 481

Question: If z and $ \omega $ are two non-zero complex numbers such that $ | z\omega |=1 $ and $ Arg(z)-Arg(\omega )=\frac{\pi }{2}, $ and $ \bar{z}\omega $ is equal to $ i^{k}, $ where k is smallest natural number then k is

Solution:

Answer: 2