Q: Which of the following nuclear equations is correctly balanced for the alpha decay of $$^{226}_{88}\text{Ra}$$?

$$^{226}_{88}\text{Ra} \$$rightarrow ^{222}$$_{86}\text{Rn} $$+ ^{4}$$_{2}\alpha$$

Question 1

A patient is prescribed 750 mg of a medication. The tablets available contain 250 mg each. How many tablets should the patient take to receive the prescribed dose?

Accepted Answer

3 tablets

Question 2

Which of the following represents a chemical change?

Accepted Answer

Burning a piece of paper

Question 3

A sample of an element contains two isotopes: 70% with a mass of 62 amu and 30% with a mass of 64 amu. What is the average atomic mass of the element? Use the weighted average formula.

Accepted Answer

$$62.6\ 	ext{amu}$$

Question 4

Which of the following statements about the periodic table is correct?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 5

A radioactive isotope has a half-life of 4 hours. If you start with 80 mg, how much remains after 12 hours?

Accepted Answer

$$10\ 	ext{mg}$$

Question 6

Which of the following nuclear equations is correctly balanced for the alpha decay of $$^{226}_{88}	ext{Ra}$$?

Accepted Answer

$$^{226}_{88}	ext{Ra} \$$rightarrow ^{222}$$_{86}	ext{Rn} $$+ ^{4}$$_{2}\alpha$$

Question 7

Which of the following best describes the difference between a compound and a mixture?

Accepted Answer

A compound contains elements chemically combined in fixed proportions; a mixture contains substances physically combined.

Question 8

Convert 98.6°F (normal human body temperature) to degrees Celsius using the appropriate formula.

Accepted Answer

$$37.0^\circ	ext{C}$$

Question 9

Which of the following electron configurations represents a neutral atom of sodium ($$	ext{Na}$$, atomic number 11)?

Accepted Answer

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

Question 10

A sample of gold has a mass of 19.3 g and a volume of 1.00 cm$$^3. $$What is the density of gold?

Accepted Answer

$$19.3\ 	ext{g/cm}^3$$

Question 11

Which of the following statements about subatomic particles is correct?

Accepted Answer

An electron has a negative charge and a mass much less than 1 amu.

Question 12

Which of the following best explains why technetium-99m is widely used in diagnostic nuclear medicine?

Accepted Answer

It emits useful gamma radiation and has a relatively short half-life.

Question 13

How many significant figures are in the measurement 0.04050 g?

Accepted Answer

4

Question 14

Which of the following describes the trend in atomic size across a period from left to right?

Accepted Answer

Atomic size decreases.

Question 15

A neutral atom of chlorine has a mass number of 35. How many neutrons does it have?

Accepted Answer

17

Question 16

Which of the following is a correct statement about nuclear fusion?

Accepted Answer

Fusion is the process by which the Sun produces energy.

Question 17

A substance has a melting point of $$0^\circ	ext{C}$$ and a boiling point of $$100^\circ	ext{C}. $$What is its physical state at $$50^\circ	ext{C}$$?

Accepted Answer

Liquid

Question 18

Which of the following best describes beta-minus ($$\beta^-) $$emission?

Accepted Answer

The atomic number increases by 1 and the mass number remains unchanged.

Question 19

Which of the following is the correct chemical formula for a compound containing 2 sodium atoms and 1 oxygen atom?

Accepted Answer

$$	ext{Na}_2	ext{O}$$

Chemistry 1120 Exam 1 Study Guide: Matter, Measurement, Atomic Structure, and Nuclear Chemistry

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