Questions

Explanations

36 In the formula for the compound XCl₄, the X could represent

(1) C       (3) Mg

(2) Η        (4) Zn

37 The formula C₂H₄ can be classified as

(1) a structural formula, only

(2) a molecular formula, only

(3) both a structural formula and an empirical formula

(4) both a molecular formula and an empirical formula

its not a structure

so it is only a molecular formula

38 Given the balanced equation representing a reaction:

4Al(s) + O₂(g) --> 2Al₂O₃(s)

How many moles of  Al(s) react completely with 4.50 moles of  O₂(g)to produce 3.00 moles of  Al₂O₃(s)?

(1) 1.50 mol      (2) 2.00 mol

 (3) 6.00 mol      (4) 4.00 mol

3.00mol/2Al₂O₃ =  x mol/4Al

39. What is the percent composition by mass of oxygen in Ca(NO₃)₂ (gram-formula mass=164 g/mol)?

(1) 9.8%     (3) 48%

(2) 29%      (4) 59% 

40 Given the balanced equation representing a reaction:

6Li +N₂ --> 2Li₃N

Which type of chemical reaction is represented by this equation?

(1) synthesis               (2) decomposition

(3) single replacement (4) double replacement