P is a white solid. Gentle heating releases CO₂ (a white precipitate forms in the limewater) + water vapour (droplets) — the white solid hardly changes, and there is no effervescence from a dry solid. With solution Q, P effervesces (CO₂ again) and a light blue precipitate settles.
Q = copper(II) chloride: Ba(NO₃)₂ → no observable change (no sulfate); AgNO₃ → white precipitate (Cl⁻); ammonia slowly → light blue precipitate, which dissolves in excess → dark blue solution (Cu²⁺); NaOH → light blue precipitate insoluble in excess. CO₂ was obtained from P → P is a carbonate (CO₃²⁻).
Indicator I is green in alkali, purple in acid. Drop-count to the end-point (sample readings: R₁ = 13, R₂ = 7). More drops of acid → more of the base → R₁ is the more concentrated.
Written observations are checked offline against the mark scheme's points; the two drop counts are marked numerically. The feedback tells you what's missing so you can edit and re-mark.