Question

When x molecules are removed from 200 mg of
N20, 2.89 x 10-3 moles of N20 are left. x will be
(1) 1020 molecules
(2) 1010 molecules
(3) 21 molecules
(4) 1021 molecules
​

Answer 1

Answer:

Here, initial moles of N2O=

44

200×10

−3

=4.55×10

−3

moles removed = initial - final =4.55×10

−3

−2.89×10

−3

=1.66×10

−3

moles

∴ no of molecules removed =6.022×10

23

×1.66×10

−3

=9.996×10

20

≈10×10

20

≈10

21

molecules

Hence, the correct option is D