Question

calculate mass of 1.505 ×10^23 molcules of oxygen gas

Answer 1

32g of 02 contains 6.022 multiply by 10^23 molecules.
From above we can observe that,
6.022 Multiply by 10^23 molecule are in 32g of 02.
Then,
1.505 Multiply by 10^23 molecule will have

1.505 Multiply by 10^23 divided by 6.022 multiply by 10^23 multiply by 32 g of O2.

Hope you get your answer.

Answer 2

Atoms & Molecules,

We know that 1 mole or 6.023x10²³molecule of oxygen weights(2 × 16)gm = 32gm.

Therefore, 1 molecule of O2 will weight = 32/6.023x10²³gm

So, 1.505x10²³ molecules of O2 will weight = 1.505x10²³x32/6.023x10²³gm.
which is 48.16/6.023 or estimately 7.996 gm.

That's it
Hope it helped (｡ŏ﹏ŏ)