Which one of the following is used in the preparation of styrene?

$A$ candle of diameter $d$ is floating on a liquid in a cylindrical container of diameter $D$ $(D >> d)$ as shown in the figure. If it is burning at the rate of $2 \ cm/hour$,then the top of the candle will

The major product of the following reaction is :

$A$ large open tank has two holes in the wall. One is a square hole of side $L$ at a depth $y$ from the top and the other is a circular hole of radius $R$ at a depth $4y$ from the top. When the tank is completely filled with water,the quantities of water flowing out per second from the two holes are the same. Then the value of $R$ is

Which of the following reagents will convert propionic acid to $1-propanol$?

In a step-up transformer, the turn ratio is $1:2$. A Leclanche cell $(e.m.f. 1.5\,V)$ is connected across the primary. The voltage developed in the secondary would be.......$V$