Calculate the number of molecules in 9.00 moles h2s.

5.42 x 10²⁴

Explanation:

There is a number called Avogrado's constant, and this constant is:

6.022 x 10²³

The reason that this number is so important in chemistry calculations, is that it is the exact number of atoms in a mole of that substance.

Calculations:

No. of molecules = (Avogrado's constant) x n  (where n is the moles)

No. of molecules = (6.022 x 10²³) x (9 moles)

No. of molecules = 5.42 x 10²⁴

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e