The frequency of a light ray is $6 \times 10^{14} \ Hz$. Its frequency when it propagates in a medium of refractive index $1.5$ will be:

If the curves $y^2=6x$ and $9x^2+by^2=16$ intersect each other at right angles,the value of $b$ is

Which of the following oxides is the anhydride of orthophosphoric acid $(H_3PO_4)$?

If the charge on the capacitor is increased by $2 \ C$,the energy stored in it increases by $21 \%$. The total original charge on the capacitor is: (in $C$)

Which of the following is a hormone-releasing $IUD$?

Two blocks of masses $10\,kg$ and $4\,kg$ are connected by a spring of negligible mass and placed on a frictionless horizontal surface. An impulse gives a velocity of $14\,m/s$ to the heavier block in the direction of the lighter block. The velocity of the centre of mass is ......... $m/s$.