Which of the following is $NOT$ an effect of the filarial worm?

Which of the following supports a dense population of plankton and littoral vegetation?

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

If $(2, 0)$ is the vertex and the $y$-axis is the directrix of a parabola,then its focus is

When a tuning fork of frequency $341 \ Hz$ is sounded with another tuning fork,six beats per second are heard. When the second tuning fork is loaded with wax and sounded with the first tuning fork,the number of beats is two per second. The natural frequency of the second tuning fork is (in $Hz$)

$A$ weightless thread can bear a tension up to $3.7\,kg-wt$. $A$ stone of mass $500\,g$ is tied to it and revolved in a circular path of radius $4\,m$ in a vertical plane. If $g = 10\,ms^{-2}$,then the maximum angular velocity of the stone will be ......... $rad\,s^{-1}$