3. the chemical equation for what happened to the zinc in the boiling sodium hydroxide is written below:
zn (s) + 2 naoii (aq) + 2 h20 (1) ► nazzn(oii)4 (aq) + ii2 (g)
does this equation represent a physical change or a chemical change? how do you know?
physical change

Chemical change  

Explanation:

Zn(s) + 2NaOH(aq) + 2H₂O(ℓ) ⟶ Na₂Zn(OH)₄(aq) + H₂(g)

A chemical change involves the formation of new substances with different properties.

The solid zinc disappeared, and a gaseous substance was formed, so this was a chemical change.

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

i think it's c. if you look search electronic symbol on google and then click on wiki it shows you a