$\int \frac{x^8-9 x^2+18}{x^4-3 x^2+3} d x=$

The volume of an air bubble becomes three times as it rises from the bottom of a lake to its surface. Assuming atmospheric pressure to be $75\, cm$ of $Hg$ and the density of water to be $1/10$ of the density of mercury,the depth of the lake is ....... $m$.

Doctors use a stethoscope to hear the sounds produced during each cardiac cycle. The second heart sound is heard when:

Given below are two statements regarding silent heart attack.
Statement $I$: This type of heart attack shows symptoms like chest pain and shortness of breath.
Statement $II$: In this type of heart attack,usually person shows very mild symptoms and thus it is ignored.
In the light of above two statements,choose the correct answer from options given below.

Which of the following species has no $p\pi - p\pi$ bond but has a bond order equal to that of $O_2$?

Power supplied to a particle of mass $2\,kg$ varies with time as $P = \frac{3t^2}{2}\,W$. Here $t$ is in seconds. If the velocity of the particle at $t = 0$ is $v = 0$,the velocity of the particle at time $t = 2\,s$ will be .............. $m/s$.