Calculate molar mass of a solute at 300 K if 400 mg of it is dissolved in 300 mL of water exerts osmotic pressure of 0.2 atm .

$$\left(\mathrm{R}=0.0821 \mathrm{~L} \mathrm{~atm} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}\right)$$

According to carbinol system tert-butyl alcohol is named as

A system performs mechanical work equal to 15 kJ and looses 2 kJ of heat to surrounding. What is the change in internal energy of a system?

What is the designation of an orbital with quantum numbers $\mathrm{n}=4$ and $l=3$?