Question 1

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 2

A magnesium atom has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

$$12$$

Question 3

Which of the following best explains why water is a polar molecule?

Accepted Answer

Oxygen is more electronegative than hydrogen, causing electrons to be shared unequally.

Question 4

What is the correct formula for calculating pH?

Accepted Answer

$$\mathrm{pH} = -\log [\mathrm{H}^+]$$

Question 5

Which of the following is NOT a property of water that is important for life?

Accepted Answer

Water is hydrophobic.

Question 6

If the pH of a solution changes from 6 to 4, how does the concentration of $$\mathrm{H}^+$$ ions change?

Accepted Answer

It increases by 100 times.

Question 7

Which of the following best describes an ionic bond?

Accepted Answer

A bond formed by the transfer of electrons from one atom to another.

Question 8

What is the main function of a buffer system in biological fluids?

Accepted Answer

To minimize shifts in pH by pairing a weak acid and its conjugate base.

Question 9

Which of the following elements is the most electronegative?

Accepted Answer

Fluorine

Question 10

A solution has a pH of 2. What is the concentration of $$\mathrm{H}^+$$ ions in moles per liter?

Accepted Answer

$$1 	imes 10$$^{-2}$$

Question 11

Which of the following best describes a covalent bond?

Accepted Answer

A bond formed by sharing a pair or pairs of electrons between atoms.

Question 12

What is the total number of atoms in one molecule of glucose ($$\mathrm{C}_6\mathrm{H}_{12}\mathrm{O}_6$$)?

Accepted Answer

$$24$$

Question 13

Which of the following statements about elements is FALSE?

Accepted Answer

Atoms of different elements can have the same number of protons.

Question 14

Which of the following is a real-life example of a buffer system in the human body?

Accepted Answer

Carbonic acid-bicarbonate system in blood.

Question 15

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

Accepted Answer

Water expands and becomes less dense when it freezes due to hydrogen bonding.

Question 16

Which of the following is a salt, as defined in chemistry?

Accepted Answer

NaCl

Question 17

Which of the following molecules contains a nonpolar covalent bond?

Accepted Answer

$$\mathrm{N}_2$$

Question 18

What is the main attractive force responsible for surface tension in water?

Accepted Answer

Hydrogen bonds between water molecules.

Question 19

Which of the following best describes the role of electronegativity in chemical bonding?

Accepted Answer

It determines how strongly an atom attracts electrons in a bond.

Question 20

Which of the following is true about acids and bases?

Accepted Answer

Acids donate $$\mathrm{H}^+$$ ions when dissolved in water; bases accept $$\mathrm{H}^+$$ ions or release $$\mathrm{OH}^-$$ ions.

Chemical Foundations: Basic Chemistry for Cells

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