The bond angles of $NH_3$,$NH_4^+$,and $NH_2^-$ are in the order :-

If $b+c=3a$,then $\cot \frac{B}{2} \cot \frac{C}{2}$ is equal to :

Let $Q$ be the set of all rational numbers in $[0,1]$ and $f:[0,1] \rightarrow [0,1]$ be defined by $f(x) = \begin{cases} x & \text{for } x \in Q \\ 1-x & \text{for } x \notin Q \end{cases}$. Then,the set $S = \{x \in [0,1] : (f \circ f)(x) = x\}$ is equal to

$A$ smooth sphere $A$ is moving on a frictionless horizontal plane with an angular velocity $\omega$ and a linear velocity $v$ of its center of mass. It undergoes an elastic head-on collision with an identical sphere $B$ which is at rest. If there is no friction anywhere,then after the collision,their angular speeds are $\omega_A$ and $\omega_B$ respectively. Then:

It includes multicellular,aquatic or terrestrial,photosynthetic eukaryotic organisms.

........ of a reaction cannot be determined experimentally.