Science Homework Help

QUESTION 2

1. A compound has the empirical formula CH2O and a formula mass of 120.10 amu.

What is the molecular formula of the compound?

A.C4H8O4B.C3H6O3C.C2H4O2D.CH2OQUESTION 3

1. How many grams of NaOH are in 500.0 mL of 2.65 M NaOH solution?
2. A.53.0 g
3. B.5.30 x 102 g
4. C.0.0189 g
5. D.1.33 g

QUESTION 4

1. Determine the percentage of calcium ion in Ca3(PO4)2 .
2. A.38.765%
3. B.12.92%
4. C.19.97%
5. D.2.5797%

QUESTION 5

1. A compound of carbon and hydrogen contains 92.3% C and has a molar mass of 78.1 g/mol. Select all that is correct.
2. A.The empirical formula is CH.
3. B.The molecular formula is C8H8.
4. C.The molecular formula is C6H6.
5. D.There is not enough information for us to determine the molecular and the empirical formulas.

QUESTION 6

1. What is the percentage by mass of O in Cu4(AsO3)2(CH3CO2)2?
2. 3.863%
3. 25.885%
4. 14.866%
5. 6.727%

QUESTION 7

1. A 250-mL sample of 1.25 M NaOH solution is prepared by dissolving an amount of 5.28 M NaOH. Select all that is correct.
2. A.59.2 mL of the 5.28 M NaOH was used in the dilution.
3. B.The moles of NaOH transferred from the 5.28 M NaOH solution are equal to the number of moles in the 250-mL sample of the NaOH solution.
4. C.-There are fewer moles of NaOH in the dilute solution than in the amount of the concentrated solution used.
5. D.1.69 x 10-2  mL

QUESTION 8

1. What is the molar concentration of sodium ions in 0.652 M sodium sulfate solution?
2. A.0.652 M
3. B.1.30 M
4. C.0.326 M
5. D.0.767 M

QUESTION 9

1. A sample of pure copper has a mass of 16.35 g. How many moles does this mass correspond to?
2. A.3.887 mol
3. B.1.549 x 1023 mol
4. C.0.2573 mol
5. D.2.715 x 10-23 mol

QUESTION 10

1. Which sample contains the greatest number of atoms?
2. A.25 g Cu
3. B.25 g F2
4. C.25 g Ne 
5. D.25 g Ba

QUESTION 11

1. If a compound has a ratio of one nitrogen to two hydrogen, what is the percentage of nitrogen in the compound?
2. A.87.5%
3. B.66.7%
4. C.33.3%
5. D.12.5%