because the x value is not repeated twice as it is in {(-8, -2), (7, -2),(-9,2), (0,0) {(5,8), (9,7),(-3,-8),(5,-5)} {(7,-8), (7, - 7), (8,4),(1, -3)}
Science and technology have had a major impact on society, and their impact is growing. By drastically changing our means of communication, the way we work, our housing, clothes, even the length, and quality of life itself, science has generated changes in the moral values and basic philosophies of mankind.
Any of these could work. Nitrogen has 5 valence electrons so you just needed to pick an element that has 3 valence electrons that nitrogen could borrow. This periodic table shows valence electron counts:
In the diagram, the ship send sound(?) waves to the water, to determine if there is anything there. If there is something like a sunken ship shown in the diagram, the waves return in a shorter time hence you can understand if theres something or now. This is the principle of radars and sonars.