A chemical change involves a change in . A chemical change involves a change in . phase the elements of a molecule how atoms are bonded all of the above

All of the above.

Explanation:

Chemical changes occur when a substance combines with another to form a new substance, called chemical synthesis or, alternatively, chemical decomposition into two or more different substances.

This process is not reversible and a change of energy that is sometimes heat is given off.

yes

explanation:

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atomic mass

239 + 1 = y + 134 + 3 combine like terms

240 = y + 137             subtract 137 from both terms

240 - 137 = y

103 = y

atomic number

94 = z +54 + 0

94 = z + 54               subtract 54 from both sides.

40 = z

answer