Question 12.

12.  Regarding the acid-base neutralization reaction

Mg(OH)2 (aq) + 2 HNO3 (aq) —» 2 H2O (l) + Mg(NO3)2 (aq),

which of the following statements is true? (Points : 5)

       Mg(OH)2 is the acid and HNO3 is the salt

       Mg(OH)2 is the base and H2O is the salt

       HNO3 is the base and Mg(NO3)2 is the salt

       HNO3 is the acid and Mg(NO3)2 is the salt

  Question 13.

13.  In the combustion reaction shown below, 26.0 g of  C 2 H 2 (g) was burned, and 72.4 g of CO 2 (g)  was produced.  Calculate the percent yield.

 

2 C 2 H 2 (g)   + 5 O 2 (g)­ →  4 CO 2 (g)  + 2 H 2 O   (g)

 

(Points : 5)

       100%

       88%

       82.3%

       86.5%

  Question 14.

14.  Which of the following statements is true ? (Points : 5)

       Real gases occupy no space at all.

       Ideal gases exist in nature.

       Real gas molecules have absolutely no attractive forces between them.

       Collisions between real gas molecules are mostly, but not always entirely, elastic.

  Question 15.

15.  In the acid-base neutralization reaction Pb(NO3)2 (aq) + 2 KI (aq) —» 2 KNO3 (aq) + PbI2 (s), what are the spectator ions? (Points : 5)

       Pb +2 and NO3 -1 

       Pb+2 and I -1

       K +1 and I -1

       K +1 and NO3 -1

  Question 16.

16.  In a net ionic equation, ionic charges are not written or shown for __________. (Points : 5)

       Spectator ions

       Oxidizing agents

       Reducing agents

       Precipitates

  Question 17.

17.  In the reaction below, which substance gains electrons?

2 Fe 2 O­ 3   (s)+ 3 C   (s) →  4 Fe   (s)  + 3 CO 2 (g)

(Points : 5)

       Fe

       O

       C

       This reaction does not contain any elements which gain electrons.

  Question 18.

18.  In the reaction below, which substance is the reducing agent?

2 Fe 2 O­ 3   (s)+ 3 C   (s) →  4 Fe   (s)  + 3 CO 2 (g)

(Points : 5)

       Fe 2 O­ 3

       C

       Fe

       CO 2

  Question 19.

19.  After four half-lives, what percentage of the original radioactive sample remains? (Points : 5)

       25%

       0.4%

       6.25%

       40%

 

 Question 20.

20.  25 mL of 0.80 M HCl was titrated with NaOH.  If 37.5 mL of NaOH were required to reach the endpoint, what was the molarity of the NaOH? (Points : 5)

       1172 M

       750 M

       1.2 M

       0.53 M