Question 1

A beaker contains 100 mL of NaOH solution at pH = 13. A technician carefully pours into the beaker 10 mL of HCl at pH = 1. Which of the following statements correctly describes the results of this mixing?

Accepted Answer

A)  The concentration of Na+ ion will rise. 
B)  The concentration of Cl- ion will be 0.1 M. 
C)  The concentration of undissociated H2O molecules will remain unchanged. 
D)  The pH of the beaker's contents will be neutral. 
E)  The pH of the beaker's contents will decrease.

Question 2

One of the buffers that contributes to pH stability in human blood is carbonic acid (H2CO3). Carbonic acid is a weak acid that, when placed in an aqueous solution, dissociates into a bicarbonate ion (HCO3-) and a hydrogen ion (H+). Thus, H2CO3 ↔ HCO3- + H+
If the pH of the blood increases, one would expect

Accepted Answer

A)  a decrease in the concentration of H2CO3 and an increase in the concentration of HCO3-. 
B)  an increase in the concentration of H2CO3 and a decrease in the concentration of HCO3-. 
C)  a decrease in the concentration of HCO3- and an increase in the concentration of H+. 
D)  an increase in the concentration of HCO3- and a decrease in the concentration of OH-. 
E)  a decrease in the concentration of HCO3- and an increase in the concentration of both H2CO3 and H+.

Question 3

Trace elements are those required by an organism in only minute quantities. Which of the following is a trace element that is required by humans and other vertebrates, but not by other organisms such as bacteria or plants?

Accepted Answer

A)  nitrogen 
B)  calcium 
C)  iodine 
D)  sodium 
E)  phosphorus

Question 4

You have a freshly prepared 1 M solution of glucose in water. You carefully pour out a 100-mL sample of that solution. How many glucose molecules are included in that 100-mL sample?

Accepted Answer

A)  6.02 × 1023 
B)  3.01 × 1023 
C)  6.02 × 1024 
D)  12.04 × 1023 
E)  6.02 × 1022

Question 5

A strong acid like HCl

Accepted Answer

A)  ionizes completely in an aqueous solution. 
B)  increases the pH when added to an aqueous solution. 
C)  reacts with strong bases to create a buffered solution. 
D)  is a strong buffer at low pH. 
E)  both ionizes completely in aqueous solutions and is a strong buffer at low pH.

Question 6

One liter of a solution of pH 9 has how many more hydroxyl ions (OH-) than 1 L of a solution of pH 4?

Accepted Answer

A)  5 times more 
B)  32 times more 
C)  50,000 times more 
D)  10,000 times more 
E)  100,000 times more

Question 7

Nitrogen (N) is much more electronegative than hydrogen (H). Which of the following statements is correct about the atoms in ammonia (NH3)?

Accepted Answer

A)  Each hydrogen atom has a partial positive charge; the nitrogen atom has a partial negative charge. 
B)  The nitrogen atom has a full positive charge; each hydrogen atom has a full positive charge. 
C)  Each hydrogen atom has a partial negative charge; the nitrogen atom has a full positive charge. 
D)  The nitrogen atom has a partial positive charge; each hydrogen atom has a partial negative charge. 
E)  There are covalent bonds between the hydrogen atoms and polar bonds between each hydrogen atom and the nitrogen atom.

Question 8

If a salamander relied on hydrogen bonds to cling to surfaces, what type of surface would cause the most problems for this animal?

Accepted Answer

A)  a surface coated with a thin film of water 
B)  a surface made with carbon and hydrogen atoms covalently bonded together 
C)  a surface made with carbon, hydrogen, and oxygen atoms covalently bonded together 
D)  a surface made with carbon, hydrogen, nitrogen, and oxygen atoms covalently bonded together 
E)  a surface made with silicon and oxygen atoms covalently bonded together

Question 9

A 0.01 M solution of a substance has a pH of 2. What can you conclude about this substance?

Accepted Answer

A)  It is a strong acid that ionizes completely in water. 
B)  It is a strong base that ionizes completely in water. 
C)  It is a weak acid. 
D)  It is a weak base. 
E)  It is neither an acid nor a base.

Question 10

Figure 2.6
-What is the atomic number of the cation formed in the reaction illustrated in Figure 2.6?

Accepted Answer

A)  1 
B)  8 
C)  10 
D)  11 
E)  16

Question 11

The atomic number of chlorine is 17. The atomic number of magnesium is 12. What is the formula for magnesium chloride?

Accepted Answer

A)  MgCl 
B)  MgCl2 
C)  Mg2Cl 
D)  Mg2Cl2 
E)  MgCl3

Question 12

You have two beakers. One contains pure water, the other contains pure methanol (wood alcohol). The covalent bonds of methanol molecules are nonpolar, so there are no hydrogen bonds among methanol molecules. You pour crystals of table salt (NaCl) into each beaker. Predict what will happen.

Accepted Answer

A)  Equal amounts of NaCl crystals will dissolve in both water and methanol. 
B)  NaCl crystals will not dissolve in either water or methanol. 
C)  NaCl crystals will dissolve readily in water but will not dissolve in methanol. 
D)  NaCl crystals will dissolve readily in methanol but will not dissolve in water. 
E)  When the first crystals of NaCl are added to water or to methanol, they will not dissolve; but as more crystals are added, the crystals will begin to dissolve faster and faster.

Question 13

How many molecules of glycerol (C3H8O3; molecular mass = 92) would be present in 1 L of a 1 M glycerol solution?

Accepted Answer

A)  1 × 106 
B)  14 × 6.02 × 1023 
C)  92 × 6.02 × 1023 
D)  6.02 × 1026 
E)  6.02 × 1023

Question 14

If the cytoplasm of a cell is at pH 7, and the mitochondrial matrix is at pH 8, this means that

Accepted Answer

A)  the concentration of H+ ions is tenfold higher in the cytoplasm than in the mitochondrial matrix. 
B)  the concentration of H+ ions is tenfold higher in the mitochondrial matrix than in the cytoplasm. 
C)  the concentration of H+ ions in the cytoplasm is 7/8 the concentration in the mitochondrial matrix. 
D)  the mitochondrial matrix is more acidic than the cytoplasm. 
E)  the concentration of H+ ions in the cytoplasm is 8/7 the concentration in the mitochondrial matrix.

Question 15

A given solution contains 0.0001(10-4) moles of hydrogen ions (H+) per liter. Which of the following best describes this solution?

Accepted Answer

A)  acidic: will accept H+ from both strong and weak acids 
B)  basic: will accept H+ from both strong and weak acids 
C)  acidic: will give H+ to weak acids, but accept H+ from strong acids 
D)  basic: will give H+ to weak acids, but accept H+ from weak acids 
E)  acidic: will give H+ to both strong and weak acids

Exam 2: The Chemical Context of Life