Which of the following is a hydride?

In short-day plants,flowering is induced by:

Identify $A$ and $B$ in the following reactions:

In a compound microscope,the focal length of the objective lens is $1.2 \ cm$ and the focal length of the eyepiece is $3.0 \ cm$. When the object is kept at $1.25 \ cm$ in front of the objective,the final image is formed at infinity. The magnifying power of the compound microscope is:

$A$ student connects a long air-cored coil of manganin wire to a $100\, V$ $D.C.$ supply and records a current of $25\, A$. When the same coil is connected across a $100\, V$,$50\, Hz$ $A.C.$ supply,the current reduces to $20\, A$. The reactance of the coil is ...... $\Omega$.

Let $z = \cos \theta + i \sin \theta$. Then the value of $\sum_{m=1}^{15} \operatorname{Im}(z^{2m-1})$ at $\theta = 2^{\circ}$ is