The disadvantage of using common names for species is that

If $2 x^2-3 x y+y^2+x+2 y-8=0$, then $\frac{d y}{d x}$ is equal to

$A$ man is watching two trains,one leaving and the other coming with equal speed of $4\,m/s$. If they sound their whistles each of frequency $240\,Hz$,the number of beats per second heard by the man will be equal to (velocity of sound in air $= 320\,m/s$)

In the $NO_3^-$ ion,what are the number of bond pairs and lone pairs of electrons on the $N$ atom,respectively?

How many major groups have recent researchers classified the plant kingdom into?

Beats are produced by two waves $y_1 = a \sin(1000\pi t)$ and $y_2 = a \sin(998\pi t)$. The number of beats heard per second is: