One mole of nitrogen dioxide has 6.02 x 10²³ nitrogen dioxide molecules. if nitrogen dioxide is made of one nitrogen atom and two oxygen atoms, then one mole of nitrogen dioxide will weigh grams.
since nitrogen dioxide has a density of 1.5 grams/milliliter, then one mole of nitrogen dioxide will occupy milliliters of space.

(i got 46.01 and 31.) is this correct? if not, show your work and round your answer using the correct number of significant digits.

molar Mass = 46.01

Volume = 31

Part One

The 6.02*10^23 is not used here. What you are asked for to begin with is the molar mass of NO2. That comes off the periodic table. Since all periodic tables vary slightly, I could get an answer that is just a bit different from the one you have. I'm going to use whole numbers. It is the calculation that is important, not the sig digs.

1 nitrogen =   1 *  14  = 14 grams/mole

2 oxygens=   2 * 16 = 32 grams/mole

1 Mole = 46 grams / mole

Part Two

Formula

Density = mass / volume

Givens

Density = 1.5 grams / mL

Mass = 46 grams

Volume = ???

Solution

1.5 = 46 / volume                          Multiply both sides by volume

1.5*volume = 46/volume * volume

1.5*volume = 46                            Divide by 1.5

volume = 46/1.5

Volume = 30.7

Since 1.5 only has 2 sig digs, the answer should be 31.

1.solid

2.carbon dioxide

3.helium