We use the equation of motion for vertical component,
Here, 
is displacement of bullet, 
is vertical initial velocity of bullet which is equal to zero because bullet was fired horizontally, and t is time of flight.
Therefore,
Given, 
Substituting the values, we get time of flight
B: Extension Lines! You could have just searched this up on google
Answer:
The number of protons can be found by looking at the atomic number
Explanation:
Its at the very top of the little element box
