Answer:
elements in the same column have the same number of neutrons. elements with similar mass are placed in the same column.
 
        
                    
             
        
        
        
The refractive index for glycerine is 

, while for air it is 

.
When the light travels from a medium with greater refractive index to a medium with lower refractive index, there is a critical angle over which there is no refraction, but all the light is reflected. This critical angle is given by:

where n1 and n2 are the refractive indices of the two mediums. If we susbtitute the refractive index of glycerine and air in the formula, we find the critical angle for this case:
 
 
        
        
        
Answer:
208
Explanation:
add it together for the answer
 
        
             
        
        
        
Answer:
C: Variation in the value of g as the pendulum bob moves along its arc.
Explanation:
The formula for period of a simple pendulum is given by;
T = 2π√(L/g)
Where;
L is length
g is acceleration due to gravity 
Now, from this period equation, it is clear that the only thing that can affect the period of a simple pendulum are changes to its length and acceleration due to gravity.
Looking at the options, the only one that talks about either the length or gravity as being potential causes of the error is option C