If the normal to the curve $y = f(x)$ at the point $(3, 4)$ makes an angle $\frac{3\pi}{4}$ with the positive $x$-axis,then $f'(3)$ is equal to

What type of polymer is natural rubber?

$A$ manometer connected to a closed tap reads $4.5 \times 10^5 \, Pa$. When the tap is opened,the reading of the manometer falls to $4 \times 10^5 \, Pa$. The velocity of the flow of water is ........ $m/s$.

Water from a tap emerges vertically downwards with initial velocity $4 ~m/s$. The cross-sectional area of the tap is $A$. The flow is steady and pressure is constant throughout the stream of water. The distance $h$ vertically below the tap, where the cross-sectional area of the stream becomes $\frac{2}{3} A$, is $(g=10 ~m/s^2)$ (in $~m$)

The catalyst used for the polymerization of olefins is....

Name the blood cells,whose reduction in number can cause clotting disorder,leading to excessive loss of blood from the body.