Nitrogen isotopes don't have a charge.
 
        
             
        
        
        
Answer:
D
Explanation:
Maybe your question is meant to be: which is not a wedge, because wedge is a combination of two inclined planes, use to separate bodies which are held together by large forces. Option A,B & C are all wedge except D.
 
        
                    
             
        
        
        
Answer:

Explanation:
from snells law we have following relation
 
 is refractive index of air
 is refractive index of air
n' -  refractive index of air below
i is angle of incidence = 90 - 1.30 = 88.70^o
r is refraction angle
 plugging all value in above formula 


 
        
             
        
        
        
The elements found in the Group 1, or the Alkali Metal Group, have electronic configurations that end in 

.This means that they have 1 electron readily available to release in order to achieve a stable state. 
When these atoms release the valence electron, they will achieve a stable state. For example, Lithium's stable state will be 

 and Sodium will be 

. 
The oxidation state will then be +1. 
The answer is C.