Two chemistry questions (mathematical)?

Question

After 12 months I am reviewing for a final acs exam and here are two old timers. Answer what you please.

The volume of 0.150-molar NaHCO3 (FW = 84.0) solution that contains 6.30g of Na2CO3 is

a. 0.200L.

b. 0.400L.

c. 0.500L.

d. 1.60L.

e 2.50L.

ANSWER IS C FOR HELP

Second:

What volume of nitrous oxide, N2O, has the same number of ATOMS as 10.0L of neon at the same temperature and pressure?

a. 1.67 L

b. 2.50 L

c. 3.33 L

d. 7.50L

e. 10.0L

ANSWER IS C FOR HELP

Answer 1

Volume x molarity = moles

So find the moles in 6.3 g of sodium-bicarb.

substitute in:  V x 0.15 = (6.3/84)

Neon is a uniatomic gas.  N2O is triatomic.   10 L of each gas at a given T and P yields equal MOLES, but not atoms.