Branched chain lipids occur in the cell membranes of

$A$ line segment $l$ of length $a \ cm$ is rotated about a vertical line $L$ keeping the line $l$ in one of the following three positions: $(I)$ $l$ is parallel to $L$ and is at a distance of $r \ cm$ from $L$,$(II)$ $l$ is perpendicular to $L$ and its mid-point is at a distance $r \ cm$ from $L$,$(III)$ $l$ and $L$ are in the same plane and $l$ is inclined to $L$ at an angle $30^{\circ}$ with its mid-point at a distance $r \ cm$ from $L$. Let $A_1, A_2, A_3$ be the areas so generated. If $r > (a / 2)$,then

When the temperature of a black body increases,it is observed that the wavelength corresponding to maximum energy changes from $0.26 \mu m$ to $0.13 \mu m$. The ratio of the emissive powers of the body at the respective temperatures is

What is skin cancer called?

$A$ thin liquid film formed between a $U$-shaped wire and a light slider supports a weight of $1.5 \times 10^{-2} \ N$ (see figure). The length of the slider is $30 \ cm$ and its weight is negligible. The surface tension of the liquid film is (in $N/m$)

If $y = (\cos x^2)^2$,then $\frac{dy}{dx}$ is equal to: