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Water, pH and Macromolecules MCQ Questions & Answers

Water, pH and Macromolecules MCQs : This section focuses on the "Water, pH and Macromolecules". These Multiple Choice Questions (MCQs) should be practiced to improve the Water, pH and Macromolecules skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.

Question 1

A solution with pH = 5 is __________ than a solution with pH = 7.

A. 2 times more basic
B. 10 times more basic
C. 10 times more acidic
D. 100 times more acidic

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Question 2

The dissociation constant of H2O at 25° C is

A. 10-14 M
B. 1014 M
C. 10-7 M
D. 107 M

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Question 3

What is the concentration, in moles/liter, of the hydrogen ion, if pH of a solution is 7?

A. 7
B. 7 x 10-7
C. 5 x 10-7
D. 1 x 10-7

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Question 4

H2O and CH4 are both examples of

A. molecules
B. ions
C. acids
D. none of these

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Question 5

The elements oxygen, nitrogen, and carbon

A. can all form covalent bonds with other elements
B. contain protons and neutrons in their atomic nuclei
C. are common elements in the molecules that make up living organisms
D. All of the above

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Question 6

Which of the following will easily dissolve in a polar solvent?

A. gasoline (heptanes & octanes)
B. methane
C. argon
D. sodium chloride

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Question 7

Polyprotic acids such as H3PO4, can act as acid-base buffers

A. only in combination with polyprotic bases
B. if their concentration is kept low
C. at pH values around neutrality
D. at pH values around any of their pKa's

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Question 8

The main difference between an acid and a base is that

A. bases are polar molecules and acids are not
B. acids are polar molecules and bases are not
C. bases donate hydrogen ions in water while acids accept hydrogen ions
D. acids donate hydrogen ions in water while bases accept hydrogen ions

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Question 9

Weak acids generally have pKa

A. values less than 1
B. pKa values greater than 2
C. been seldom found in living systems
D. that cannot be used to buffer

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Question 10

The effectiveness or capacity of a buffer solution can be affected by

A. molar concentration of the buffer components
B. concentration of the conjugate base to the weak acid
C. both (a) and (b)
D. temperature of buffer components

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Question 11

Which of the following alcohols would be most soluble in water?

A. methanol
B. ethanol
C. butanol
D. octanol

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Question 12

The lone pair electrons on oxygen in a H20 molecule

A. carry a partial positive charge
B. are not important for the properties of water
C. carry a partial negative charge
D. form covalent bonds in ice

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Question 13

Buffer solutions

A. will always have a pH of 7
B. are rarely found in living systems
C. cause a decrease in pH when acids are added to them.
D. tend to maintain a relatively constant pH.

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Question 14

The reason that fats contain more energy than simple sugars, is fats have many more

A. carbon atoms
B. hydrogen atoms
C. covalent bonds
D. hydrogen bonds

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Question 15

The pH of a solution is determined by

A. concentration of salt
B. relative concentration of acids and bases
C. dielectric constant of the medium
D. environmental effect

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Question 16

Which of the following indicates that the pK of an acid is numerically equal to the pH of the solution when the molar concentration of the acid and its conjugate base are equal?

A. Michaelis-Menten equation
B. Haldanes equation
C. Henderson-Hasselbalch equation
D. Hardy-Windberg law

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Question 17

Which of the following acid/base pairs act as natural buffers in living systems?

A. H2CO3/HCO3-
B. H2PO4-/HPO42-
C. Histidine+/histidine
D. All of these

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Question 18

Which of the following organic groups are found in naturally occuring amino acids?

A. Guanidinium ion
B. Indole
C. Imidazole
D. All of these

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Question 19

Molecules in which the atoms are held together by __________ bonds have the strongest chemical linkages.

A. noncovalent
B. covalent
C. ionic
D. hydrogen

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Question 20

If protein is made exclusively from nonpolar amino acids, then it will this protein interact with water?

A. be repelled by water
B. It will be attracted to water
C. It will form a membrane in water
D. It will act as a buffer and stabilize the pH

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Question 21

A Bronsted acid becomes __________ upon losing a proton.

A. highly reactive
B. its conjugate acid
C. its conjugate base
D. a hydronium ion

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Question 22

Most of the important functional groups in biological molecules contain

A. oxygen and/or nitrogen and are acidic
B. oxygen and a phosphate
C. nitrogen and a phosphate
D. oxygen and/or nitrogen and are polar

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Question 23

Which of the following statements about water is correct?

A. It is critical for many of the chemical processes found in living systems
B. Polar substances that can form hydrogen bonds will dissolve in it
C. Nonpolar substances like oils are not soluble in it
D. All of the above

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Question 24

The strength of an acid depends on

A. number of neutrons gain
B. electronegativity
C. number of double bonds
D. number of protons released

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Question 25

Who discovered and described the blood groups (ABO) classification?

A. Theodor Kocher
B. Karl Landsteiner
C. Otto Warburg
D. Karl Hooper

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Question 26

A biological polymer contains alanine, tyrosine, and lysine. Which of the following will be true about this molecule?

B. Strong base
C. Phospholipid
D. Protein

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Question 27

The reactions of molecules

A. are the reactions of the functional groups
B. are independent of the functional groups
C. require an enzyme in all cases
D. all of the above

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Question 28

A compound that is capable of forming hydrogen bonds with water

A. is probably held together by noncovalent bonds
B. contains at least some polar covalent bonds
C. should act as a good buffer for acids and bases
D. does not dissolve well in water

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Question 29

Which of the following statements about covalently bonded molecules is false?

A. Electrons are shared between the atoms that make up the molecule
B. Noncovalent bonds may also be present, especially if the molecule is large
C. Such molecules often result from the interaction of ionized atoms
D. The chemical bonds that hold the molecule together are relatively strong

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Question 30

Salt dissolves well in water as water molecules

A. form hydrogen bonds with the positively and negatively charged ions
B. make nonpolar covalent bonds with the positively charged ions only
C. surround the ions because of their charge but do not form hydrogen bonds
D. share electrons with the ions to make polar covalent bonds

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Question 31

Which of the following character does not apply to water?

A. The water molecule is asymmetric
B. The water molecule readily forms hydrophobic interactions
C. The covalent bonds in water are highly polarized
D. All three atoms in the water molecule readily form hydrogen bonds

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Question 32

Hydrogen bonds and hydrophilic interactions are types of

A. weak chemical bonds that hold together the atoms within a molecule
B. strong chemical bonds that hold together the atoms within a molecule
C. weak chemical bonds that link together separate molecules
D. strong chemical bonds that link together separate molecules

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