Consider the following two statements :

Statement p :
The value of sin 120^o can be derived by taking $$\theta = {240^o}$$ in the equation
2sin$${\theta \over 2} = \sqrt {1 + \sin \theta } - \sqrt {1 - \sin \theta } $$

Statement q :
The angles A, B, C and D of any quadrilateral ABCD satisfy the equation
cos$$\left( {{1 \over 2}\left( {A + C} \right)} \right) + \cos \left( {{1 \over 2}\left( {B + D} \right)} \right) = 0$$

Then the truth values of p and q are respectively :

A body of mass 2 kg slides down with an acceleration of 3 m/s² on a rough inclined plane having a slope of $${30^o}$$. The external force required to take the same body up the plane with the same acceleration will be : (g = 10 m/s²)

The characteristic distance at which quantum gravitational effects are significant, the Planck length, can be determined from a suitable combination of the fundamental physical constants G, h and c.

Which of the following correctly gives the Planck length ?

A proton of mass m collides elastically with a particle of unknown mass at rest. After the collision, the proton and the unknown particle are seen moving at an angle of 90^o with respect to each other. The mass of unknown particle is :