How many molecules are in a 0.756 mole sample of sodium chloride (NaCl)?

Describe the difference between a. a hypothesis and a theory and b. an observation and an experiment.

Suppose a lab group reports a ppercent yield of sand of 105. is it really possible to collect more sand than was originally represented? what is the possible explanation for the extra product?

Sum of brother and sisters age is 26. four times the brothers age is subtracted from three times the sisters age, the difference is 8. what are the ages of the brother and sister?