There are two valence electrons.
Answer:
All elements in the same group of the periodic table have the same number of valence electrons. This made it possible to compare the valence of the alien elements to the valence of elements from our periodic table, and match the alien elements to the correct group. For example, our group 14 elements all have 4 valence electrons, so the alien element with 4 valence electrons had to be part of group 14 also.
15. D is correct, exothermic reactions release heat
I am not sure about 16
<span>The answer is deceleration. Acceleration is the general term to refer to the change in velocity. Acceleration = change in velocity / change in time. When you want to highlight the fact that the change in velocity is a decrease in the magnitude, you can use the term deceleration, which means that the acceleration is negative.</span>
All of the above will be affected by air resistance, but the most obvious will be the balloon or leaf.
Hope it helps somewhat!
