Q: Which of the following is a correct conversion factor for changing 5.0 meters to centimeters?

$$1 \ \text{m} = 100 \ \text{cm}$$

Q: A nutrition label states that a food contains 9 g of fat, 4 g of protein, and 12 g of carbohydrates. Using the energy values (fat: 9 kcal/g, protein: 4 kcal/g, carbohydrate: 4 kcal/g), what is the total energy content of the food?

$$(9 \times 9) + (4 \times 4) + (12 \times 4) = 81 + 16 + 48 = 145 \ \text{kcal}$$

Q: A sample of water is heated from 25°C to 75°C. If the mass of water is 100 g and the specific heat of water is $$4.18 \ \text{J/g} \cdot \text{°C}$$, how much energy is required?

$$q = m \times c \times \Delta T = 100 \times 4.18 \times (75 - 25) = 100 \times 4.18 \times 50 = 20,900 \ \text{J}$$

Q: Which of the following is the correct formula for calculating density?

$$\text{Density} = \dfrac{\text{mass}}{\text{volume}}$$

Question 1

Which of the following statements best describes a scientific method in chemistry?

Accepted Answer

It is a systematic approach involving hypothesis, observation, experimentation, and conclusion.

Question 2

A student measures the mass of a sample three times and gets values of 2.01 g, 2.03 g, and 2.02 g. The accepted value is 2.50 g. Which statement best describes the accuracy and precision of these measurements?

Accepted Answer

The measurements are precise but not accurate.

Question 3

Which of the following is a correct conversion factor for changing 5.0 meters to centimeters?

Accepted Answer

$$1 \ 	ext{m} = 100 \ 	ext{cm}$$

Question 4

A nutrition label states that a food contains 9 g of fat, 4 g of protein, and 12 g of carbohydrates. Using the energy values (fat: 9 kcal/g, protein: 4 kcal/g, carbohydrate: 4 kcal/g), what is the total energy content of the food?

Accepted Answer

$$(9 	imes 9) + (4 	imes 4) + (12 	imes 4) = 81 + 16 + 48 = 145 \ 	ext{kcal}$$

Question 5

Which of the following is an example of a physical change?

Accepted Answer

Melting ice into water

Question 6

A sample of water is heated from 25°C to 75°C. If the mass of water is 100 g and the specific heat of water is $$4.18 \ 	ext{J/g} \cdot 	ext{°C}$$, how much energy is required?

Accepted Answer

$$q = m 	imes c 	imes \Delta T = 100 	imes 4.18 	imes (75 - 25) = 100 	imes 4.18 	imes 50 = 20,900 \ 	ext{J}$$

Question 7

Which of the following best describes an element?

Accepted Answer

A pure substance consisting of only one type of atom.

Question 8

Which of the following is the correct formula for calculating density?

Accepted Answer

$$	ext{Density} = \dfrac{	ext{mass}}{	ext{volume}}$$

Question 9

Which of the following is NOT a correct statement about isotopes?

Accepted Answer

Isotopes of an element have different atomic numbers.

Question 10

Which of the following is the correct electron configuration for a neutral atom of sodium (Na, atomic number 11)?

Accepted Answer

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

Question 11

Which of the following best describes a mixture?

Accepted Answer

A combination of two or more substances that retain their individual properties.

Question 12

Which of the following is a correct statement about the periodic table?

Accepted Answer

Elements in the same group have similar chemical properties.

Question 13

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

Accepted Answer

10 g

Question 14

Which of the following types of radiation has the greatest penetrating power?

Accepted Answer

Gamma ($$\gamma) $$radiation

Question 15

Which of the following is the correct formula for calculating the energy required to change the temperature of a substance?

Accepted Answer

$$q = m 	imes c 	imes \Delta T$$

Question 16

Which of the following is a chemical property?

Accepted Answer

Ability to react with oxygen

Question 17

A patient receives a dose of 0.5 Ci of a radioactive isotope. How many disintegrations per second does this represent? ($$1 \ 	ext{Ci} = 3.7 	imes 10$$^{10}$$ \ 	ext{disintegrations/sec})$$

Accepted Answer

$$0.5 	imes 3.7 	imes 10$$^{10}$$ = 1.85 	imes 10$$^{10}$$ \ 	ext{disintegrations/sec}$$

Question 18

Which of the following best describes the difference between mass number and atomic number?

Accepted Answer

Mass number is the sum of protons and neutrons; atomic number is the number of protons.

Question 19

Which of the following is the correct order of electromagnetic radiation from lowest to highest energy?

Accepted Answer

Radio waves \u003c Visible light \u003c X-rays \u003c Gamma rays

GOB Chemistry Study Notes: Chapters 1–5 (Chemistry in Our Lives, Measurements, Matter & Energy, Atoms & Elements, Nuclear Chemistry)

Guida di studio - Domande di pratica

Study guide - Flashcard