Which of the following instruments is used to measure the rate of transpiration in plants?

What is the current through an ideal $P-N$ junction diode shown in the figure below? (in $mA$)

In which of the following reactions is an aromatic aldehyde treated with an acid anhydride in the presence of the corresponding salt of the acid to give an unsaturated aromatic acid?

The maximum tension a rope can withstand is $60 ~kg-wt$. The ratio of maximum acceleration with which two boys of masses $20 ~kg$ and $30 ~kg$ can climb up the rope at the same time is

An engine giving a whistle is moving towards a stationary observer with a speed of $110\,m/s$. What will be the ratio of the frequency of the whistle heard when the engine is approaching and receding from the observer? (The speed of sound is $330\,m/s$.)

If $y = \log_{\cos x} \sin x$,then $\frac{dy}{dx}$ is equal to