A buffer solution is prepared by mixing 0.2 M sodium acetate and 0.1 M acetic acid. If pK$$_a$$ for acetic acid is 4.7, find the pH.

A solution of nonvolatile solute is obtained by dissolving $$3.5 \mathrm{~g}$$ in $$100 \mathrm{~g}$$ solvent has boiling point elevation $$0.35 \mathrm{~K}$$. Calculate the molar mass of solute.

(Molal elevation constant $$=2.5 \mathrm{~K} \mathrm{~kg} \mathrm{~mol}^{-1}$$ )

At $$0{ }^{\circ} \mathrm{C}$$ a gas occupies 22.4 liters. What is the temperature in Kelvin to reach the volume of 224 liters?

Which from following rule / principle states that "No two electrons in an atom can have the same set of four quantum numbers"?