What is the number of unpaired electrons in Ti in +3 state?

Calculate the total number of tetrahedral and octahedral voids formed in 0.6 mol of a compound if it forms hcp structure.

Calculate the concentration of dissolved gas in water at $25^{\circ} \mathrm{C}$ if partial pressure of gas at same temperature is 0.15 atm .

$$ \left[\mathrm{K}_{\mathrm{H}}=0.15 \mathrm{~mol} \mathrm{dm}^{-3} \mathrm{~atm}^{-1}\right] $$

Which from following is an essential amino acid?