For a first order reaction, (A) $$\to$$ products, the concentration of A changes from 0.1 M to 0.025 M in 40 minutes. The rate of reaction when the concentration of A is 0.01 M is :

Which method of purification is represented by the following equation :
Ti (s) + 2I₂ (g) $$\buildrel {523K} \over \longrightarrow $$ TiI₄ (g) $$\buildrel {1700K} \over \longrightarrow $$ Ti (s) + 2I₂ (g)

The molecule having smallest bond angle is :

Iron exhibits + 2 and +3 oxidation states. Which of the following statements about iron is incorrect?