Answer:
2 litres of pure alcohol will be added to make the overall concentration of 9 litres of mixture as 30%.
Explanation:
Suppose x is the number of litres added to the 10% mixture than the quantity of new mixture is given as below
litres
litres
Also the quantity of alcohol is given as
Now the equation is as

So 2 litres of pure alcohol will be added to make the overall concentration of 9 litres of mixture as 30%.
Valence bond theory stating that a bond between two atoms is the strongest when the nuclei of the atoms are touching each other is true.
<h3>What is Valence bond theory?</h3>
This theory states that when two valence orbitals of two different atoms overlap on each other, the bond is usually strong.
The bond formed in this scenario is usually covalent which involves sharing of the valence electrons.
Read more about Valence bond theory here brainly.com/question/11625586
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Classical physics that matter cannot be created or destroyed in an isolated <span>system</span>
H........................................
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