From which plant is cocaine obtained?

Which of the following pairs is incorrectly matched?

Consider the following standard electrode potentials ($E^o$ in volts) in aqueous solution:

Element	$M^{3+}/M$	$M^{+}/M$
$Al$	$-1.66$	$+0.55$
$Tl$	$+1.26$	$-0.34$

Based on these data,which of the following statements is correct?

$A$ motor of power $P_0$ is used to deliver water at a certain rate through a given horizontal pipe. To increase the rate of flow of water through the same pipe $n$ times,the power of the motor is increased to $P_1$. The ratio of $P_1$ to $P_0$ is

$\int \frac{1+\cos 4 x}{\cot x-\tan x} d x$ is equal to

The molarity of a $0.2 \ N \ Na_2CO_3$ solution will be .......... $M$.