Q: Which of the following is a correct example of a simple (one-step) conversion factor problem?

Converting 100 cm to meters using $$1 \\ \mathrm{m} = 100 \\ \mathrm{cm}$$

Q: A hospital stores oxygen gas at 25°C. What is this temperature in Kelvin, and why is the Kelvin scale preferred in scientific calculations?

$$298.15 \\ \mathrm{K}$$; Kelvin is preferred because it starts at absolute zero, making calculations involving temperature and energy more accurate.

Question 1

Which of the following lists the correct steps of the scientific method in order?

Accepted Answer

Observation, Hypothesis, Experiment, Analysis, Conclusion

Question 2

How many significant figures are in the measurement 0.00450?

Accepted Answer

3

Question 3

A student measures the mass of a sample as 12.30 g and its volume as 4.0 mL. What is the density, reported with the correct number of significant figures?

Accepted Answer

$$3.1 \ \mathrm{g/mL}$$

Question 4

Which of the following is the correct electron configuration for calcium (atomic number 20)?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^2$$

Question 5

Which subatomic particles are found in the nucleus of an atom?

Accepted Answer

Protons and neutrons

Question 6

An isotope of carbon has 6 protons and 8 neutrons. What is its mass number?

Accepted Answer

14

Question 7

If a potassium ion has a charge of $$+1$$, what is its electron configuration?

Accepted Answer

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

Question 8

Which quantum number describes the shape of an orbital?

Accepted Answer

Azimuthal quantum number ($$l)$$

Question 9

Convert 25.0 °C to Kelvin.

Accepted Answer

$$298.15 \ \mathrm{K}$$

Question 10

A sample contains 70% chlorine-35 and 30% chlorine-37. What is the average atomic mass of chlorine? (Atomic masses: $$^{35}\mathrm{Cl} = 34.97$$, $$^{37}\mathrm{Cl} = 36.97)$$

Accepted Answer

$$35.54$$

Question 11

Which of the following is the correct symbol for the element with atomic number 26?

Accepted Answer

Fe

Question 12

A 10.0 g sample of a compound contains 4.0 g of element X. What is the percent by mass of X in the compound?

Accepted Answer

$$40\%$$

Question 13

Which of the following best describes the electron configuration of a neutral fluorine atom?

Accepted Answer

$$1s^2$$ $$2s^2$$ $$2p^5$$

Question 14

Which of the following is a correct example of a simple (one-step) conversion factor problem?

Accepted Answer

Converting 100 cm to meters using $$1 \ \mathrm{m} = 100 \ \mathrm{cm}$$

Question 15

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same number of protons but different numbers of neutrons.

Question 16

Which element has the electron configuration $$1s^2$$ $$2s^2$$ $$2p^6$$ $$3s^2$$ $$3p^6$$ $$4s^1$$?

Accepted Answer

Potassium

Question 17

A sample of iron contains 90% $$^{56}\mathrm{Fe} ($$atomic mass = 55.93) and 10% $$^{54}\mathrm{Fe} ($$atomic mass = 53.94). What is the average atomic mass?

Accepted Answer

$$55.73$$

Question 18

Which quantum number determines the energy level of an electron in an atom?

Accepted Answer

Principal quantum number ($$n)$$

Question 19

Which of the following is the correct electron configuration for a neutral sodium atom?

Accepted Answer

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

Question 20

A hospital stores oxygen gas at 25°C. What is this temperature in Kelvin, and why is the Kelvin scale preferred in scientific calculations?

Accepted Answer

$$298.15 \ \mathrm{K}$$; Kelvin is preferred because it starts at absolute zero, making calculations involving temperature and energy more accurate.

Introduction to Chemistry: Study Guide and Electron Configuration Reference

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