Answer:
Consider frames X and Y:
If X sees Y moving to his right then Y must see X moving to his right.
If this is not true then one can choose one frame over the other ( a favored frame and this is not allowed)
 
        
             
        
        
        
Answer:
C. The facial feedback theory
Explanation:
The facial feedback theory as postulated by William James and connects back to the famous Charles Darwin talks about how facial expressions stimulate our emotional state of being. Based on this theory, the emotional experiences we have are determined by the looks on our faces. 
According to the question, smiling at an event makes you enjoy it is an example of what the The facial feedback theory is explaining. Furthermore, smiling, which is a facial expression causes or stimulates an emotional state of enjoyment in that event. 
 
        
             
        
        
        
Hey there!:
Here the Statement - D is correct.  
Because Orbitals containing the core electrons are more attracted towards nuclear charge and hence less shilded from nuclear charge than an orbital that doesn't penetrate.  Also due to more attraction between the orbital containing core electron and nucleus, it will have less energy. 
Hope this helps!
 
        
             
        
        
        
Answer:
The answer is false
Explanation:
 Though the mostly used SI unit of measurement or the most popular units are the 
Length,
Time and 
Mass
i.e meter (m), seconds (s), kilogram (kg)
 
Aside all the above stated units for measurements there are other four basic units which are itemized  bellow.
they are
1. Amount of substance - mole (mole)
2. Electric current - ampere (A)
3. Temperature - kelvin (K)
4. Luminous intensity - candela (cd)
 
        
             
        
        
        
Answer: ZnSO4 + Li2CO3 = ZnCO3 + Li2SO4 - Chemical Equation Balancer
Equation is already balanced.
Explanation: ZnSO4 + Li2CO3 = ZnCO3 + Li2SO4