Question 1

Which of the following best describes a chemical change?

Accepted Answer

Iron rusting when exposed to air

Question 2

Which statement about mixtures and compounds is correct?

Accepted Answer

Mixtures can be separated by physical means and do not have a fixed composition.

Question 3

A student measures the mass of a sample as 2.3456 g. If the answer must be reported to three significant figures, what is the correct value?

Accepted Answer

2.35 g

Question 4

Which of the following is the correct electron configuration for a neutral atom of chlorine (atomic number 17)?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ $$3s^2$$\ $$3p^5$$

Question 5

Which of the following ions is isoelectronic with neon ($$Ne$$)?

Accepted Answer

$$Na^+$$

Question 6

What is the formula for calcium phosphate?

Accepted Answer

$$Ca_3$$($$PO_4)_2$

Question 7

Which of the following best describes the difference between ionic and covalent compounds?

Accepted Answer

Ionic compounds are formed by transferring electrons, while covalent compounds are formed by sharing electrons.

Question 8

Which of the following is the correct balanced equation for the reaction of aluminum with oxygen to form aluminum oxide?

Accepted Answer

$$4Al + 3O_2 \rightarrow 2Al_2O_3$$

Question 9

A chemical reaction has the following equation: $$2H_2 + O_2$ \rightarrow 2H_2O. If $$you start with 4 moles of $$H_2$$ and excess $$O_2$$, how many moles of $$H_2O$$ will be produced?

Accepted Answer

4 moles

Question 10

Which of the following statements about activation energy is correct?

Accepted Answer

Activation energy is the energy required to start a chemical reaction.

Question 11

Which of the following gases would diffuse the fastest at room temperature?

Accepted Answer

$$H_2$$

Question 12

Which of the following solutions is most likely to conduct electricity?

Accepted Answer

A solution of sodium chloride in water

Question 13

Which of the following is a Brønsted-Lowry acid?

Accepted Answer

$$HCl$$

Question 14

If the $$[H^+] in a $$solution is $$1 	imes 10$$^{-4}$$ M, what is the pH?

Accepted Answer

pH = 4

Question 15

Which of the following is true about nuclear reactions compared to chemical reactions?

Accepted Answer

Nuclear reactions involve changes in the nucleus, while chemical reactions involve changes in electron arrangement.

Question 16

A buffer solution is made by mixing acetic acid and sodium acetate. What is the main function of this buffer?

Accepted Answer

To maintain a relatively constant pH when small amounts of acid or base are added

Question 17

Which of the following best explains why water has a high boiling point compared to other similar-sized molecules?

Accepted Answer

Water molecules form hydrogen bonds, which are strong intermolecular forces.

Question 18

Which of the following is the correct formula for calculating the molarity ($$M) of a $$solution?

Accepted Answer

$$M = \dfrac{	ext{moles of solute}}{	ext{liters of solution}}$$

Question 19

Which of the following is a correct statement about the Law of Conservation of Energy?

Accepted Answer

Energy is neither created nor destroyed, only transformed from one form to another.

Question 20

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

10 grams

Comprehensive Study Guide: GOB Chemistry Chapters 1–11

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