Thorn of $Bougainvillea$ and tendril of $Cucurbita$ are examples of

$A$ polaroid is placed at $45^{\circ}$ to an incoming light of intensity $I_0$. Now,the intensity of light passing through the polaroid after polarization would be:

What is the respective number of $\alpha$ and $\beta$ particles emitted in the following radioactive decay: ${}_{90}^{200}X \to {}_{80}^{168}Y$?

The combined equation of the diagonals of the square formed by the two pairs of straight lines given by $xy+4x-3y-12=0$ and $xy-3x+4y-12=0$ is

If two soap bubbles of different radii are connected by a tube,then

The acute angle between the two lines whose direction ratios $(l, m, n)$ satisfy the equations $l+m-n=0$ and $l^2+m^2-n^2=0$ is