To solve such this we must know the concept of double displacement reaction. Therefore, the blank should be filled with word chemical.
Chemical reaction is a process in which two or more than two molecules collide in right orientation and energy to form a new chemical compound. The mass of the overall reaction should be conserved.
There are so many types of chemical reaction reaction like combination reaction, double displacement reaction. In a chemical reaction, two or more elements or compounds form one product.
Therefore, the blank should be filled with word chemical.
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