Which statement best describes the properties of metals? They are shiny and bend without breaking.
They are dull and are good electrical insulators.
They conduct electricity well and are brittle.
They can be flattened and do not conduct heat well.

the catch is that the top numbers are atomic masses the bottom numbers are the numbers of protons and electrons in an uncharged atom. they are the number of that atoms as you would find them on the periodic table. further, the numbers on the left are used to determine the missing numbers on the right

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

Yes, endothermic means it turns cold. and some chemical changes include change of tempature.

No is the answer to the question

Olá. porque a reação na temperatura é muito rapida a do copo : )