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

Plants deficient in the element zinc show effects on the biosynthesis of which plant growth hormone?

If the lines,joining the origin to the points of intersection of the curve $2x^2 - 2xy + 3y^2 + 2x - y - 1 = 0$ and the line $x + 2y = k$,are at right angles,then $k^2$ equals

In angiosperms,the pollen tube releases its male gametes into the . . . . . . .

The angle between the curves $y=\sin x$ and $y=\cos x$ is

Which of the following products is formed when $SiF_4$ reacts with water?