What are the observations and conclusions for the exercises on mixture C regarding its properties and ionic composition?

Here are the observations and conclusions for the exercises on mixture C:

a)

• Observation: Solid C dissolves in distilled water to form a colorless solution. Blue litmus paper turns red, and red litmus paper remains red.
• Conclusion: The solution is acidic.

b)

i)

• Observation: To the first portion, adding $\text{NaOH}_{\text{(aq)}}$ dropwise produces a white precipitate. The precipitate dissolves when excess $\text{NaOH}_{\text{(aq)}}$ is added, forming a colorless solution.
• Conclusion: $\text{Zn}^{2+}$, $\text{Al}^{3+}$, or $\text{Pb}^{2+}$ ions are present.

ii)

• Observation: To the second portion, adding $\text{NH}_{3\text{(aq)}}$ dropwise produces a white precipitate. The precipitate dissolves when excess $\text{NH}_{3\text{(aq)}}$ is added, forming a colorless solution.
• Conclusion: $\text{Zn}^{2+}$ ions are present.

iii)

• Observation: To the third portion, adding $\text{BaCl}_{2\text{(aq)}}$ produces a white precipitate. The precipitate remains insoluble when dilute $\text{HCl}$ is added.
• Conclusion: $\text{SO}_4^{2-}$ (sulfate) ions are present.

iv)

• Observation: To the fourth portion, adding Fehling's solution A and B and boiling, a brick-red precipitate forms.
• Conclusion: A reducing sugar is present.