A. the distance between towns
Answer: a)
: Decomposition
b)
: double displacement
c)
: Synthesis (Combination)
d)
: redox
Explanation:
Decomposition is a type of chemical reaction in which one reactant gives two or more than two products.

A double displacement reaction is one in which exchange of ions take place.

Synthesis reaction is a chemical reaction in which two reactants are combining to form one product.

Redox reaction is a type of chemical reaction in which oxidation and reduction takes place in one single reaction. The oxidation number of one element increases and the oxidation number of other element decreases.

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(I) 
(II) 
(III) 
(IV) 
(V) 
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For 7A(17) :
Electronic configuration 
So, there are 5 unpaired electrons present in group 7A(17).
<h3>
What are Unpaired Electrons?</h3>
- An unpaired electron is an electron that doesn't form part of an electron pair when it occupies an atom's orbital in chemistry.
- Each of an atom's three atomic orbitals, designated by the quantum numbers n, l, and m, has the capacity to hold a pair of two electrons with opposing spins.
- Unpaired electrons are extremely uncommon in chemistry because an object carrying an unpaired electron is typically quite reactive. This is because the production of electron pairs, whether in the form of a chemical bond or as a lone pair, is frequently energetically advantageous.
- They play a crucial role in describing reaction pathways even though they normally only appear momentarily during a reaction on a thing called a radical in organic chemistry.
To learn more about unpaired electrons with the given link
brainly.com/question/14356000
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