Correct ratio in hydrated salts

Steps:

• Define water of crystallization as water molecules bound in a salt's crystal lattice, denoted by formula like CuSO₄·5H₂O.
• Evaluate option ratios: A claims 6:1 for CoCl₂·6H₂O, but it's 1:6 (one formula unit to six waters).
• Check B: CuSO₄·5H₂O ratio is 1:5, matching the standard formula.
• Assess C and D: C misdescribes evaporation from solution; D reverses color change on heating.

Why B is correct:

• The formula CuSO₄·5H₂O directly indicates a 1:5 ratio of anhydrous salt to water molecules, per standard chemical notation.

Why the others are wrong:

• A: Ratio is 1:6 for CoCl₂·6H₂O, not 6:1.
• C: Water of crystallization is lattice-bound, not evaporated from saturated solutions.
• D: Heating blue CuSO₄·5H₂O yields white anhydrous CuSO₄, not blue crystals.

Final answer: B