The solution to Significant figures

1. how many significant figures does the sum of the following contain? 8.520 + 2.7

2. how many moles of oxygen atoms are there in 10 moles of KCIO3

3. the oxidation number of N in NaNo3 is

4. what element is oxidized in the following chemical reaction? 3Cu + 8HNO3 ----> Cu(NO3) + 2NO + 4H2O

5. at what temp. will a fixed amount of gas with a volume of 175 L at 15C and 760 mmHg occupy a volume of 198L at a pressure of 640 mmHg

6. how many liters of chlorine gas at 200C and 0.500 atm can be produced by the reaction of 12.0 g of Mno2 with HCI as follows: MnO2(s) + 4HCl(aq) ----> MnCl2(aq) + 2H2o(l) + Cl2(g)

7. which of the following ions has the largest radius Na+, K+, Ca2+, Cl-, F-

8. which one of the following molecules does not have a dipole moment: CO, CH2Cl2, SO3, SO2, NH3

for the rest of the problems work out and observe significant digits

9. The freon propellant from an aerosol can was analyzed, and a 4.263g sample contained the following: 0.423 g carbon, 2.50 g chlorine, and 1.34 g fluorine. The molecular weight of the propellant is 244 g/mol. What is the empirical formula of the compound? What is the molecular formula of the compond?

10. A sample of gas occupies 250 mL under laboratory conditions of 27C and 740 mmHG pressure? What is the volume at standard temperature and pressure conditions?

11. What volume of carbon dioxide gas can be collected from the reaction between 10.0g of calcium carbonate and 100.0 mL of 0.50 M hydrochloric acid at 25.0C and 1.0 atm pressure? R=0.082 L *atm/K*mol