Which of these represents a chemical change?
a)
two compounds combining to form a mixture
b)
a mixture being separated into two elements
c)
a compound being separated into two elements
d)
an element changing state from solid to liquid

answer: option (a) is the correct answer.

explanation:

a chemical change is a change which occurs when chemical composition of a substance changes.

for example, when hcl is added to naoh then it results in the formation of a salt and water. this means that the chemical composition of reactants has changed.

the reaction is as follows.

thus, we can see that two compounds combine to form a mixture which is nacl in the above reaction.

whereas when we heat solid ice then it gets melted which shows that only the state has changed. hence, there is no change in its chemical composition because when we freeze liquid water then it will again turn into solid ice. therefore, it is a physical change.

hence, we can conclude that two compounds combining to form a mixture represents a chemical change.