Lavoisier proposed that all matter is composed from the same atoms elements molecules gases

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Lavoisier proposed that all matter is composed from the same elements.

Explanation: -

Lavoisier was a french chemist. He was a pioneer of stoichiometry. He proposed that all matter, irrespective of the physical state, is composed from the same elements.

Thus water, ice and water vapor all have the elements hydrogen and oxygen in the same ratio 2:1.

Lavoisier also was the one who defined the element as something which cannot be further broken down into simpler substances by any chemical means.

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