Asubstance undergoes a change. which of the following indicates that the change was a chemical change? the substance changed shape. new molecules formed. the substance froze. the substance changed size.

New molecules formed.

Explanation:

A physical change is defined as the change in which shape, size will be altered. No new substance gets formed in these reactions.

A chemical change is defined as the change in which chemical composition is altered. A new substance is formed in these reactions.

The substance changed shape is a physical change.

The substance froze means the state is changed and is a physical change.

The substance changed size is a physical change.

Thus when new molecules are formed, it is a chemical change.

it's c. elements are placed in rows based on how may valencies electrons have.

so here we go

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