Timing of Heating in Lab Procedure

Steps:

• Review the experimental procedure to identify heating instructions.
• Note heating between steps 3 and 4 for reaction completion.
• Confirm no heating between steps 2 and 3 or after step 4.
• Match to choice B as the only accurate description.

Why B is correct:

• In standard qualitative analysis procedures, heating between steps 3 and 4 dissolves precipitates or drives reactions, per solubility rules.

Why the others are wrong:

• A includes incorrect heating points not specified in the procedure.
• C omits the essential heating between steps 3 and 4.
• D is incomplete and does not describe any valid timing.

Final answer: B