Q: Which of the following is a correct use of dimensional analysis to convert $$250 \ \mathrm{mg} to $$grams?

$$250 \ \mathrm{mg} \times \frac{1 \ \mathrm{g}}{1000 \ \mathrm{mg}} = 0.250 \ \mathrm{g}$$

Question 1

Which of the following numbers is correctly written in scientific notation?

Accepted Answer

$$4.56 	imes 10$$^{3}$$

Question 2

How many significant figures are in the measurement $$0.004520$$?

Accepted Answer

4

Question 3

A patient is prescribed a medication at a dose of $$15 \ \mathrm{mg/kg}. If $$the patient weighs $$154 \ \mathrm{lb}$$, and the medication is available as $$250 \ \mathrm{mg}$$ tablets, how many tablets should be administered? (1 kg = 2.205 lb)

Accepted Answer

4 tablets

Question 4

Which of the following is a correct metric conversion for $$0.025 \ \mathrm{g} to $$milligrams?

Accepted Answer

$$25 \ \mathrm{mg}$$

Question 5

A sample of a liquid has a mass of $$32.0 \ \mathrm{g}$$ and a volume of $$40.0 \ \mathrm{mL}. $$What is its density?

Accepted Answer

$$0.800 \ \mathrm{g/mL}$$

Question 6

Which of the following best describes a compound?

Accepted Answer

A substance formed when atoms of two or more different elements combine in fixed proportions

Question 7

Which of the following is a heterogeneous mixture?

Accepted Answer

Sand and water

Question 8

Which statement correctly distinguishes between a compound and a mixture?

Accepted Answer

A compound has a fixed ratio of elements and can only be separated by chemical means, while a mixture has a variable composition and can be separated by physical means.

Question 9

Which of the following is an example of a molecule that is also an element?

Accepted Answer

$$\mathrm{O}_2$$

Question 10

A neutral atom of sodium ($$\mathrm{Na}) $$has an atomic number of 11 and a mass number of 23. How many neutrons does it have?

Accepted Answer

12

Question 11

Which subatomic particle is responsible for the chemical properties of an element?

Accepted Answer

Electron

Question 12

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 13

A sample of gold has a mass of $$19.3 \ \mathrm{g}$$ and a volume of $$1.00 \ \mathrm{cm}^3. If $$you have a gold bar with a volume of $$50.0 \ \mathrm{cm}^3$$, what is its mass?

Accepted Answer

$$965 \ \mathrm{g}$$

Question 14

Which of the following best describes the role of neutrons in the nucleus?

Accepted Answer

They help stabilize the nucleus by reducing repulsion between protons.

Question 15

Which of the following is a correct application of significant figure rules for the calculation $$3.45 	imes 2.1$$?

Accepted Answer

$$7.2$$

Question 16

A solution is prepared by dissolving $$5.00 \ \mathrm{g} of $$salt in $$95.0 \ \mathrm{g} of $$water. Which statement best describes the resulting mixture?

Accepted Answer

It is a homogeneous mixture (solution).

Question 17

Which of the following statements about elements is correct?

Accepted Answer

An element is a pure substance made of only one type of atom.

Question 18

If a neutral atom has 17 protons, 18 neutrons, and 17 electrons, what is its mass number?

Accepted Answer

35

Question 19

Which of the following is a correct use of dimensional analysis to convert $$250 \ \mathrm{mg} to $$grams?

Accepted Answer

$$250 \ \mathrm{mg} 	imes \frac{1 \ \mathrm{g}}{1000 \ \mathrm{mg}} = 0.250 \ \mathrm{g}$$

Question 20

Which of the following best explains why sodium chloride ($$\mathrm{NaCl}) $$has properties different from both sodium and chlorine?

Accepted Answer

Because it is a compound formed by a chemical change, resulting in new properties.

GOB Chemistry Study Guide: Matter, Measurement, and Atomic Structure (Chapters 2–4)

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