There are ______ molecules of methane in 0.123 mol of methane (CH4).?

Question

A.) 5

B.) 2.46 x 10^(-2)

C.) 2.04 x 10^(-25)

D.) 7.40 x 10^(22)

E.) 0.615

Thanks!

Answer 1

Test taking tip:

You remember something about a hugh number of molecules per mole

You can rule out A and E (E would be < than one molecule.)

You can rule out B and C (both are very small numbers: < 1, partial molecules again)

You guess D because all other answers don't fit.

6.022x10^23 molecules per mole x 0.123 mol = 7.40x10^22

Answer 2

D

Use Avagadro's number (6.02 x 10^23) and multiply by the number of moles that you have.

Answer 3

D.

multiply it with Avogadro's number

Answer 4

D.  Multiply .123 times Avogadro's number.

Answer 5

0.123 mol CH4 x 6.02x10^23 molecules CH4/1 mol CH4

=7.40x10^22 molecules CH4