In which of the following is the gametophytic phase reduced,short-lived,and limited to the formation of gametes?

Two oxides of nitrogen,$NO$ and $NO_2$,react together at $253 \ K$ to form a compound of nitrogen $X$. $X$ reacts with water to yield another compound of nitrogen $Y$. The shape of the anion of $Y$ molecule is:

The number of moles of electrons required to deposit $36 \ g$ of $Al$ from an aqueous solution of $Al(NO_3)_3$ is (At. wt. of $Al = 27$)

The surface of water in a water tank of cross-sectional area $750 \, cm^2$ on the top of a house is $h \, m$ above the tap level. The speed of water coming out through the tap of cross-sectional area $500 \, mm^2$ is $30 \, cm/s$. At that instant,$\frac{dh}{dt}$ is $x \times 10^{-3} \, m/s$. The value of $x$ will be $.............$.

The angle of a prism is $A.$ One of its refracting surfaces is silvered. Light rays falling at an angle of incidence $2A$ on the first surface return back through the same path after suffering reflection at the silvered surface. The refractive index $\mu$ of the prism is

In a mutational event,when adenine is replaced by guanine,it is the case of