$A$ gas mixture consists of $2$ moles of oxygen and $4$ moles of argon at temperature $T$. Neglecting all vibrational modes,the total internal energy of the system is: (in $RT$)

If $\sin {\theta _1} + \sin {\theta _2} + \sin {\theta _3} = 3,$ then $\cos {\theta _1} + \cos {\theta _2} + \cos {\theta _3} = $

Quinine,used for the treatment of malarial fever,is extracted from:

In a compound microscope,the focal lengths of the objective and the eye lens are $2.5 \, cm$ and $5 \, cm$ respectively. An object is placed at $3.75 \, cm$ before the objective and the image is formed at the least distance of distinct vision. Then,the distance between the two lenses (i.e.,the length of the microscope tube) will be......$cm$.

Menstrual flow occurs due to lack of

Which among the following reactions will take place spontaneously?