Which of the following methods is used to remove hardness from water?

In the reaction sequence,$C_2H_5Cl + KCN$ $\xrightarrow{C_2H_5OH} X$ $\xrightarrow[\Delta]{H_3O^+} Y$. What is the molecular formula of $Y$?

If the lines $\frac{x-1}{2}=\frac{y+1}{3}=\frac{z-1}{4}$ and $\frac{x-3}{1}=\frac{y-k}{2}=\frac{z}{1}$ intersect,then the value of $k$ is:

Which of the following is used in the industrial production of nitric acid by the Ostwald process?

The perimeter of a $\triangle ABC$ is $6$ times the arithmetic mean of the sine of its angles. If its side $BC$ is of unit length,then $\angle A=$

Which of the following is the preferred site for injecting medication to ensure rapid action and minimize side effects?