150/30 = 5
HF1 20/2 = 10
HF2 10/2 = 5
HF3 5/2 = 2.5
HF4 2.5/2 = 1.25
HF5 1.25/2 = 0.625
Answer: 0.63g
I believe this is a double replacement. As you can see none of the chemical symbols are missing, there just "replaced".
They are pretty much the cause and effect. The independent variable that is being changed in the experiment, so it is the cause. The dependant variable is the result of change the independant variable, so the effect.
Answer:
It would react better than what with dilute and will furnish more hydrogen gas.
1. According to Rutherford and soddy's law of Beta emission:

3. According to Rutherford and soddy's law of Alpha emission:

4. The process in which two or more light nuclei are combined to form a single nucleus with the release of tremendous amount of energy is called a nuclear fusion. The inner core of Sun is at very high temperature and is suitable for fusion. In fact the source of energy of Sun and other stars is nuclear fusion reactions.