Which kingdom is characterized by the presence of a rigid cell wall and the formation of an embryo?

$A$ tube of length $L$ is filled completely with an incompressible liquid of mass $M$ and closed at both ends. The tube is then rotated in a horizontal plane about one of its ends with a uniform angular velocity $\omega$. The force exerted by the liquid at the other end is

Which one of the following hormones,though synthesised elsewhere,is stored and released by the master gland?

If $10\%$ of a radioactive material decays in $5$ days,then the amount of original material left after $20$ days is approximately ...............$\%$

The colour of light absorbed by an aqueous solution of $CuSO_4$ is

$A$ light wave is incident normally on a slit of width $24 \times 10^{-5} \ cm$. The angular position of the second dark fringe from the central maxima is $30^{\circ}$. What is the wavelength of light in $\mathring{A}$?