In which activities other than studies should the energy of boys be utilized?

Two bodies have their moments of inertia $I$ and $2I$ respectively about their axis of rotation. If their kinetic energies of rotation are equal,their angular momenta will be in the ratio

Heat energy is incident on the surface at the rate of $1000 ~J/min$. If the coefficient of absorption is $0.8$ and the coefficient of reflection is $0.1$,then the heat energy transmitted by the surface in $5$ minutes is: (in $~J$)

If one side of a triangle is double the other and the angles opposite to these sides differ by $60^{\circ}$,then the triangle is

Which one of the following is used in the preparation of styrene?

Seven balls are drawn simultaneously from a bag containing $5$ white and $6$ green balls. The probability of drawing $3$ white and $4$ green balls is: