Why were the sample of salt and sand placed into 50-ml beakers prior to weighing?

Answer : Salt and Sand are weighed and kept in different 50 Milliliter beakers because, the experiment is about studying and separating the homogeneous mixture. As salt crystals are cubic and sand grains are rounded oblong grains. If we mix it together it would require a physical method to separate them. So, before starting the experiment it needs to be weighed in different beakers.

the millers tale is the answer.

practical process described pest part of scientific investigation.

because practical knowledge is powerful then therotical knowledge.