According to the Doppler effect, the sound of a police car siren is louder and high pitched as it approaches the observer. 
        
                    
             
        
        
        
Answer: C6H12O6
Explanation: glucose is the simplest sugar. As N is the number of the carbon atom, when we multiply 6 into the inner basic formula then (CH2O) convert into C6H12O6. As the number of carbon atom changed the formula of sugar also changed. 
 
        
             
        
        
        
Answer:
The true statement is: "Spring tides are the highest, while neap tides are the lowest."
Explanation:
- The range of difference in the level of water between high and low tide is always larger in spring tide.
- Neap tides are the moderate tides. It does not have huge difference in higher and low tides because the bulging of the ocean ( by the sun)  balances the bulge of the ocean caused by the moon.
- This balance is not found in spring tides that is the main reason for spring tides to have the highest level for both higher and lower tides.