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26 May 2022

1. Which of the following contains the smallest percentage of iron?

A. pyrite (FeS2)                                                        C.  magnetite (Fe3O4)

B. hematite (Fe2O3)                                                D. siderite (FeCO3)

 

1. How many moles of Ca atoms are there in 0.40 g of the element?

A.60                          B. 0.10                       C. 010                         D. 16               

                                                                                     

1. What is the percent nitrogen in the compound ammonium nitrate?

A.5 g                  B.  50.5 g                    C.  70.0 g                     D.  35.0 g

4. Consider the equation: NaOH +   Cl2 +   NH3   →   N2H4  +   H2O + NaCl      If 45.0 g of NaOH is allowed to react with 100 g of Cl2,which will be the limiting       reagent?

A.NaOH                          

B.  Cl2                   

C.  N2H4                                    

D. NaCl

5. How many moles of O atoms are there in 1 mole of magnesium sulfate heptahydrate?

A.7                                     

 B. 11                         

C. 4                            

D. 10

 

Solve the following problems. show your complete solution

1.Ethanol, the alcohol contained in alcoholic beverages, is composed of 52.2% C, 0% H, and oxygen. Its molar mass is 46.0 g/mol. (a) what is the empirical  formula of  ethanol? (b) What is its molecular formula? (5 points)