The precipitation of second group sulphides in qualitative analysis is carried out with hydrogen sulphide in the presence of hydrochloric acid but not in nitric acid. Explain.

If $$\tan \theta = - {4 \over 3},then\sin \theta \,is\,$$

If $$\alpha + \beta + \gamma = 2\pi ,$$ then

If the cube roots of unity are $$1,\,\omega ,\,{\omega ^2},$$ then the roots of the equation $${\left( {x - 1} \right)^3} + 8 = 0$$ are