C.
Nitrogen has the atomic no. of 7 so the proton and the electron no. is 7.
Three more electrons are needed to fulfil the octet structure: 2,8
        
             
        
        
        
Answer: Force F will be one-sixteenth of the new force when the charges are doubled and distance halved
Explanation:
Let the charges be q1 and q2 and the distance between the charges be 'd'
Mathematical representation of coulombs law will be;
F1=kq1q2/d²...(1)
Where k is the electrostatic constant.
If q1 and q2 is doubled and the distance halved, we will have;
F2 = k(2q1)(2q2)/(d/2)²
F2 = 4kq1q2/(d²/4)
F2 = 16kq1q2/d²...(2)
Dividing equation 1 by 2
F1/F2 = kq1q2/d² ÷ 16kq1q2/d²
F1/F2 = kq1q2/d² × d²/16kq1q2
F1/F2 = 1/16
F1 = 1/16F2
This shows that the force F will be one-sixteenth of the new force when the charges are doubled and distance halved
 
        
             
        
        
        
<span>vf^2 = vi^2 + 2*a*d
---
vf = velocity final
vi = velocity initial
a = acceleration
d = distance
---
since the airplane is decelerating to zero, vf = 0
---
0 = 55*55 + 2*(-2.5)*d
d = (-55*55)/(2*(-2.5))
d = 605 meters
</span>
        
             
        
        
        
Answer:
150 inches (12.5 ft)
Explanation:
The work done to lift the 500 pound block 3 inches should be the same as that to lift the 10 pond object a given distance.
The following is the equation one needs to solve:

therefore solving for the distance "x" gives as the answer (in inches):

which can also be given in feet as: 12.5 ft
 
        
             
        
        
        
Year 1972
if I'm not wrong :)