The current of 1.70 A is passed through 300.0 ml of 0.160 M solution of a ZnSO₄ for 230 sec. with a current efficiency of 90%. Find out the molarity of Zn²⁺ after the deposition of Zn. Assume the volume of the solution to remain constant during electrolysis.

The decomposition of N₂O₅ according to the equation:
2N₂O₅ (g) $$\to$$ 4NO₂(g) + O₂(g)
is a first order reaction. After 30 min. from the start of the decomposition in a closed vessel, the total pressure developed is found to be 284.5 mm of Hg and on complete decomposition, the total pressure is 584.5 mm of Hg. Calculate the rate constant of the reaction.

Write the IUPAC name for the following :

The value of
$$\sin {\pi \over {14}}\sin {{3\pi } \over {14}}\sin {{5\pi } \over {14}}\sin {{7\pi } \over {14}}\sin {{9\pi } \over {14}}\sin {{11\pi } \over {14}}\sin {{13\pi } \over {14}}$$ is equal to ______.