Which of the following is a conjugate acid-base pair?

What is the technique of obtaining a large number of plantlets by tissue culture called?

If the distance $s$ travelled by a particle in time $t$ is given by $s=t^2-2t+5$,then its acceleration is

$A$ particle is moving along a circular path with constant speed and centripetal acceleration $a$. If the speed is doubled,the ratio of its acceleration after and before the change is

The energy of an electron in the $3^{rd}$ orbit of a hydrogenic atom is $-E$. The energy of an electron in the first orbit will be

What is the respective number of $\alpha$ and $\beta$ particles emitted in the following radioactive decay: ${}_{90}^{200}X \to {}_{80}^{168}Y$?