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

If the maximum velocity with which an electron can be emitted from a photocell is $4 \times 10^8 \,cm/sec$,the stopping potential is ............ $V$ (mass of electron $= 9 \times 10^{-31} \,kg$).

If the geometric mean between $a$ and $b$ is $\frac{a^{n+1} + b^{n+1}}{a^n + b^n}$,then the value of $n$ is

At $90 \, ^\circ C$,the concentration of $[H_3O^+]$ in pure water is $10^{-6} \, M$. What is the value of $K_w$ at this temperature?

In compound $X$,all the bond angles are exactly ${109^o}28'$,$X$ is

On heating ammonium dichromate,the gas evolved is