Question 1

Which of the following best explains why perpetual motion machines are impossible according to the laws of thermodynamics?

Accepted Answer

They violate the second law because energy is always lost as heat, increasing entropy.

Question 2

A student wants to make a 1 molar solution of glucose ($$C_6H_{12}O_6$). If the molecular mass of glucose is 180 g/mol, how should the student prepare this solution?

Accepted Answer

Dissolve 180 grams of glucose in enough water to make 1 liter of solution.

Question 3

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 4

A radioactive isotope has a half-life of 10 years. If you start with 80 grams, how much will remain after 30 years?

Accepted Answer

$$80 \div 2^3$ = 10$$ grams

Question 5

Which of the following best describes a polar covalent bond?

Accepted Answer

A bond where electrons are shared unequally between atoms, resulting in partial charges.

Question 6

Which element is most likely to form hydrogen bonds in biological molecules?

Accepted Answer

Oxygen

Question 7

If an atom has 11 protons, 12 neutrons, and 10 electrons, what is its net charge and atomic mass?

Accepted Answer

Charge: $$+1$$, Mass: $$23$$ Daltons

Question 8

Which of the following is a real-world application of radioactive isotopes in medicine?

Accepted Answer

Using iodine-131 to diagnose and treat thyroid disorders.

Question 9

Which statement about chemical equilibrium is correct?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal.

Question 10

Which of the following best explains why water is a good solvent for ionic compounds?

Accepted Answer

Water is polar and can surround and separate ions due to its partial charges.

Question 11

A gecko can climb smooth walls due to which type of weak chemical interaction?

Accepted Answer

Van der Waals interactions

Question 12

Which of the following best describes the relationship between energy and entropy according to the second law of thermodynamics?

Accepted Answer

As energy is transferred or transformed, the entropy of the universe increases.

Question 13

Which of the following is NOT a property of noble gases?

Accepted Answer

They are highly reactive due to incomplete valence shells.

Question 14

Which of the following best explains why the shape of a molecule is important in biology?

Accepted Answer

The shape determines how the molecule interacts with other molecules, such as enzyme-substrate binding.

Question 15

Which of the following is an example of a chemical reaction that is essential for life and is reversible?

Accepted Answer

$$CO_2 + H_2O$$ \rightleftharpoons H_2CO_3$$

Question 16

Which of the following best describes the difference between kinetic and potential energy in biological systems?

Accepted Answer

Kinetic energy is the energy of motion, while potential energy is stored energy due to position or structure.

Question 17

Which of the following is true about ions?

Accepted Answer

An anion is negatively charged because it has gained electrons.

Question 18

If you have 46 grams of pure sodium ($$Na$$), and the atomic mass of sodium is 23, how many moles of sodium do you have?

Accepted Answer

$$\frac{46}{23} = 2$$ moles

Question 19

Which of the following best describes a hydrogen bond?

Accepted Answer

A weak attraction between a hydrogen atom covalently bonded to an electronegative atom and another electronegative atom.

Question 20

Which of the following is a correct statement about the organization of biological systems?

Accepted Answer

Cells are made of molecules, which are made of atoms.

The Chemical Context of Life: Foundations for General Biology

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