Answer:
A. Materials with a low index of refraction cause light to refract very little.
 
        
                    
             
        
        
        
Answer:
GPE = 388.08 Joules.
Explanation:
Given the following data;
Mass = 0.550kg
Speed = 335 m/s
Height = 72 meters
We know that acceleration due to gravity, g is equal to 9.8 m/s²
To find the gravitational potential energy;
Gravitational potential energy (GPE) is an energy possessed by an object or body due to its position above the earth.
Mathematically, gravitational potential energy is given by the formula;

Where;
G.P.E represents potential energy measured in Joules.
m represents the mass of an object. 
g represents acceleration due to gravity measured in meters per seconds square. 
h represents the height measured in meters. 
Substituting into the formula, we have;

GPE = 388.08 Joules.
 
        
             
        
        
        
1. First blank is A. Conductors
Second blank is D. Insulators
2. C. Heat
        
             
        
        
        
Each BB 0.349 grams and 5.386 grains. 349 mg & 5.386 grains each steel BBs.