Elements with 7 valence electrons are extremely reactive, while elements with 8 valence electrons practically don't react at all.
This is caused by the fact that all molecules want to have 8 valence electrons; that's just the scientific fact. So, if an element already has 8 valence electrons, it doesn't need to react with anything. If the element only has 7 valence electrons, however, it really wants to react with something with 1 valence electron to get to that special number 8.
Falling from an airplane.
Answer:
d) the total resistance is 4 + 5 = 9 ( ohm)
e) the current in the circuit is 18/9 = 2(A)
f) the voltage in R = 4 ohm is 2.4 = 8 (V)
the voltage in R = 5 ohm is 18 - 8 = 10 (V)
The lower case m =Apparent magnitude
