250miles is distance
5hours is time
Speed = distance/time
Speed = 250/5
Speed =50miles per hour
50mph
Hope that helps :)
Answer: TWO.
At least two groups: treatment group and control group.
The treatment group is that is exposed to the different levels of the independent variable ( a medication for example), while the control group is not treated, so the researchers can compare the effect of the medication.
Answer:
The yield is 20 %.
Explanation:
Mg + 2 HCl → MgCl2 + H2
(12 g Mg) / (24.30506 g Mg/mol) x (1 mol H2 / 1 mol Mg) x (2.015894 g H2/mol) = 0.9953 g H2.
(0.2 g) / (0.9953 g) = 0.20 = 20% yield