The volume of simple unit cell is $x \times 10^{-23} \mathrm{~cm}^3$. Calculate the value of $x$ if volume occupied by a particle in it is $2.1 \times 10^{-23} \mathrm{~cm}^3$.

What is IUPAC name of the following compound?

What is the pH of buffer solution prepared by mixing 0.01 M weak acid and 0.02 M salt of weak acid with strong base? $\left(\mathrm{pK}_{\mathrm{a}}=4.680\right)$

Calculate the entropy change of surrounding if 2 moles of $\mathrm{H}_2$ and 1 mole of $\mathrm{O}_2$ gas combine to form 2 moles of liquid water by releasing 525 kJ heat to surrounding at constant pressure and at 300 K .