Chemistry, Converting problems?

Question

3. Solve with correct significant figures: (3.08 x 10-3) x (4.90 x 10-7) =
1.51x10^10
1.5x10^9
1.5x10^10
1.51x10^9


4. Convert to moles: 3.50 g CaO:
.0625
196
1.75
3.50

5. Mole:
Quantity of a substance (6.02 x 1020) that has units of grams/mole
Quantity of a substance (6.02 x 1043) that has units of grams/mole
Quantity of a substance (6.02 x 1022) that has units of grams/mole
Quantity of a substance (6.02 x 1023) that has units of grams/mole


6. How many moles are there in 24.0 grams of carbon?
2.0
2.2
2.22
2.3


7. How many grams are there in .50 moles of carbon dioxide, CO2?
22
222
202
2.2

Answer 1

3. 1.51 x 10^-9 Your choices are incorrect.

4. 0.0625

5. One mole contains 6.022 X 10 ^-23 atoms/molecules per element/compound.

6. 2.0

7. 22g