Question

match each procedural step with its purpose.
initial rapid heating to ~20 °c below expected melting point
powdering the sample
filling only 2 - 3 mm of the capillary tube
slow heating near expected melting point
helps estimate approximate melting range
ensures uniform heat transfer
allows sharp observation of initial and final melting
prevents inaccurate readings from overpacking

Explanation:

Initial rapid heating helps estimate melting range. Powdering ensures uniform heat - transfer. Filling 2 - 3 mm allows sharp observation. Slow heating near melting point prevents inaccurate readings.

Answer:

Initial rapid heating to ~20 °C below expected melting point: Helps estimate approximate melting range
Powdering the sample: Ensures uniform heat transfer
Filling only 2 - 3 mm of the capillary tube: Allows sharp observation of initial and final melting
Slow heating near expected melting point: Prevents inaccurate readings from overpacking