2 because the 1st energy level can only hold 2 electrons and the 2nd holds 4 
 
        
             
        
        
        
when John Travoltage rubbed his foot against the floor, he started building up negative energy, this negative energy later built up as he was rubbing his foot on the floor which then caused a reaction with the door knob, the same thing happened with the balloons, as we rubbed it on the sweater, the balloons started building up negative energy too, which then resulted in a connection with the positive energy. The dust particles most likely got a charge from moving around from different places, considering that fabrics build up the negative energy, it appears that the dust particles could have landed on a fabric which then allowed the particles to build it up and then stick to other surfaces.
 
        
             
        
        
        
The names of the respiratory structures involved include the following: nasal cavities (or oral cavity) > pharynx > trachea > primary bronchi (right & left) > secondary bronchi > tertiary bronchi > bronchioles > alveoli.
<h3>What is respiration?</h3>
Respiration is defined as the oxygenation of blood through the intake of oxygen and the removal of carbon dioxide.
The pathway of oxygen gas molecule from the surrounding air through the respiratory system to the blood include respectively the following:
- Nasal cavities (or oral cavity): This has a direct association with the outside oxygen from the environment.
- pharynx: This so also called the throat.
- trachea: This is also called the wind pipe.
- Primary bronchi (right & left): This divides from the trachea to form two bronchi.
Learn more about respiration here:
brainly.com/question/2809259
#SPJ1
 
        
             
        
        
        
Answer:
Toothpaste
Explanation:
Toothpaste commonly uses minerals like calcium and fluoride, hope this helps :)
 
        
                    
             
        
        
        
A control group is important for an experiment because it allows the experiment to minimize the changes in all other variables except the one being tested.