$$pH = -\log_{10}(1 \times 10$$^{-4}$$) = 4$$

Question 1

Which of the following statements best explains why water is an excellent solvent for ionic and polar substances?

Accepted Answer

Water molecules have a bent shape and partial charges, allowing them to form hydrogen bonds with ions and polar molecules.

Question 2

A carbon atom has an atomic number of 6 and a mass number of 14. How many neutrons does this atom have?

Accepted Answer

$$14 - 6 = 8$$ neutrons

Question 3

Which property of water is primarily responsible for the phenomenon of surface tension, allowing insects to walk on water?

Accepted Answer

Cohesion between water molecules due to hydrogen bonding

Question 4

Which of the following best describes the difference between a polar covalent bond and a nonpolar covalent bond?

Accepted Answer

In a polar covalent bond, electrons are shared unequally, resulting in partial charges on the atoms.

Question 5

Which of the following functional groups acts as a base by attracting a proton?

Accepted Answer

Amino group

Question 6

If the concentration of hydrogen ions in a solution is $$1 	imes 10$$^{-4}$$ M, what is the pH of the solution?

Accepted Answer

$$pH = -\log_{10}(1 	imes 10$$^{-4}$$) = 4$$

Question 7

Which statement correctly describes the role of buffers in biological systems?

Accepted Answer

Buffers minimize changes in pH, helping maintain homeostasis.

Question 8

Which of the following molecules would be least likely to dissolve in water?

Accepted Answer

Methane ($$CH_4)$$

Question 9

Which of the following best explains why ice floats on liquid water?

Accepted Answer

Hydrogen bonds in ice create an open crystal structure, making ice less dense than liquid water.

Question 10

Which of the following is true about the first law of thermodynamics?

Accepted Answer

Energy is conserved; it can be transferred or transformed but not created or destroyed.

Question 11

A chemical reaction is considered spontaneous if:

Accepted Answer

The products have lower potential energy and/or higher entropy than the reactants.

Question 12

Which of the following best describes the difference between an ionic bond and a covalent bond?

Accepted Answer

Ionic bonds involve the complete transfer of electrons, resulting in charged ions that are attracted to each other.

Question 13

Which of the following statements about carbon is correct?

Accepted Answer

Carbon forms four covalent bonds, allowing for a limitless array of molecular shapes.

Question 14

Which of the following reactions represents the dissociation of water?

Accepted Answer

$$H_2O \rightarrow H^+ + OH^-$$

Question 15

Which of the following best explains why sweating cools the body?

Accepted Answer

Evaporation of sweat requires breaking hydrogen bonds, absorbing heat from the skin.

Question 16

Which of the following is a consequence of water's high specific heat for living organisms?

Accepted Answer

Water resists changes in temperature, helping organisms maintain stable internal conditions.

Question 17

Which of the following best describes a condensation (dehydration) reaction?

Accepted Answer

A reaction in which two monomers are joined together, resulting in the loss of a water molecule.

Question 18

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes of an element have the same number of protons but different numbers of neutrons.

Question 19

Which of the following best describes the relationship between electronegativity and the position of an element on the periodic table?

Accepted Answer

Electronegativity increases as you move up and to the right.

Water and Carbon: The Chemical Basis of Life – Study Notes

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