Using the periodic table to choose the element that matches each description include the following below:
<h3>What is a Periodic table?</h3>
This contains elements which are arranged according to the order of their atomic number in a tabular form. There are 18 groups which are the vertical columns present while there are 8 periods which are the horizontal rows present in the periodic table.
Example of an alkali metal is potassium while the non reactive ones include argon, neon etc. Examples of halogens include chlorine, iodine etc. are the ones which have seven electrons in their outer electron shells thereby just requiring one electron to achieve to obtain a stable octet configuration.
These are therefore the elements which match the descriptions provided in this case and is the most appropriate choice.
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The pressure of the gas = 40 atm
<h3>Further explanation</h3>
Given
200 ml container
P = 2 atm
final volume = 10 ml
Required
Final pressure
Solution
Boyle's Law
At a fixed temperature, the gas volume is inversely proportional to the pressure applied

Input the value :
P₂ = P₁V₁/V₂
P₂ = 2 x 200 / 10
P₂ = 40 atm
Answer:
When two forces are the same strength but act in opposite direction, they are called balanced forces. Again, tug-of-war is a perfect example. If the people on each side of the rope are pulling with the same strength, but in the opposite direction, the forces are balanced. The result is no motion.
Explanation:
Hope this helps!
There are 5 valence electrons in a atom of phosphorus.