Which of the following represents a surfactant molecule?

$A$ public park,in the form of a square,has an area of $(100 \pm 0.2) \; m^2$. The side of the park is ............ $m$.

The period of $\left(\tan \theta - \frac{1}{3} \tan^3 \theta\right) \left(\frac{1}{3} - \tan^2 \theta\right)^{-1}$,where $\tan^2 \theta \neq \frac{1}{3}$,is

Assertion $(A)$: Equal moles of different substances contain the same number of constituent particles.
Reason $(R)$: Equal weights of different substances contain the same number of constituent particles.
The correct answer is

If the pair of straight lines given by $Ax^2+2Hxy+By^2=0$ $(H^2 > AB)$ forms an equilateral triangle with the line $ax+by+c=0$,then $(A+3B)(3A+B)$ is equal to:

The angle between the lines $2x = 3y = -z$ and $6x = -y = -4z$ is ......... $^o$.