Answer:
second energy level
Explanation:
Valence electrons are those electrons which are present in outer most orbital of the atom.
This can be easily found through the electronic configuration of atom.
Electronic configuration of F:
F₉ = 1s² 2s² 2p⁵
We can see that the valence electrons are present in second energy level of F atom.
There are seven valence electrons of fluorine.
It is called halogens.
Halogens are very reactive these elements can not be found free in nature. Their boiling points also increases down the group which changes their physical states. i.e fluorine is gas while iodine is solid.
Fluorine:
1. it is yellow in color.
2. it is flammable gas.
3. it is highly corrosive.
4. fluorine has pungent smell.
5. its reactions with all other elements are very vigorous except neon, oxygen, krypton and helium.
Avagadro's law gives the relationship between volume of gas and amount of moles of gas. It states that at constant temperature and pressure, volume of gas (V) is directly proportional to number of moles of gas (n).
V/n = k
where k - constant

V1 = 42.0 L
n1 = 1.90 mol
n2 = 1.90 mol - 0.600 = 1.30 mol
substituting the values in the equation

V = 28.7 L
Volume of the gas is 28.7 L
Answer: a: reactants Na-2 Cl-2
Products: Na-2 Cl-2;
b: reactants P-1 Cl-13 H-6 Products P-1 H-6 Cl-13
c: reactants P-4 H-12 O-16
Products H-12 P-4 O-16
Explanation: since these equations are balanced the atoms on of element on the reactants side will be same as the atoms of the same element of the product side
A physical property is a property that does not change the original substance, meaning that it does not break any bonds, nor for any new ones. Though, a physical property can be changing the substances state of matter.
When you are boiling water, you are changing its state to go from a liquid to a gas. The temperature is not a characteristic physical property because it doesn't help us know a lot about that substance, in other words, it isn't significant to the substance. Same goes for volume.