Answer:
Scientific Method. 
Explanation:
A scientific method is basically a method or a process when you conduct an experiment. Normally, the process goes like this: 
1. You make like a question or something that you want to investigate, it's like the aim of the experiment. 
2. You make an experiment and a hypothesis. A hypothesis is basically a guess on how the results of the experiment would turn out. You don't have to be correct for the hypothesis since there is no right or wrong answer. 
3. Conduct the experiment. I don't think this needs a detailed explanation since experiments vary from one another. 
4. Collect results. The data you collect come in different ways based on your experiment, but it is crucial you get data so that you can answer your question in 1. 
5. Make inferences. You can't directly get a conclusion or answer from the results, so inferences are needed. 
6. Craft a conclusion or answer. This is the final step when conducting an experiment and the part where you have the answer you needed when you conducted the experiment :) 
 
        
             
        
        
        
First off chlorine is not a metal so you can ignore that one. 
Sodium and Rubidium are in group 1 of the periodic table and Magnesium is in group 2.
Group one metals are more reactive than group two because it is harder for the group two metals to lose their 2 valence (outer most) electrons. 
As you go down group 1 there is an increase in the reactivity this is because as you go down there is an increase in the atomic radius which leads to more shielding. This weakens the electrostatic forces of attraction making it easier to lose the outermost electrons, therefore they are more reactive.
        
             
        
        
        
Answer:r=1.2 d=2.4
Explanation:
Radius is half the diameter and the diameter is 2.4 m
 
        
                    
             
        
        
        
Answer:
The End Result Of Diffusion Is An Equal Concentration, Or Equilibrium, Of Mocules On Both Sides Of The Membrane. 
Explanation:
☺️ Hope It helps Ty.