- The reaction in which we can't take back the product to reactant form .Or in simple words the reaction which is irreversible is called chemical reaction
Example:-
We cannot pull back the reaction to get wax back .
Answer:
A. Solution, Colloid, Suspension
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In 2009, the US Geological Survey estimated the Arctic may be home to 30% of the planet's natural gas reserves and 13% of oil.
Answer:

Explanation:
Combination reactions are the reactions in which two or more atoms/ molecules combine to give a single product.
Aluminum metal combines with iodine to given aluminium iodide.
Aluminium has a valency of 3 and iodine has valency of 1, so the formula is 
The reaction is shown below as:
