Question 1

Which of the following is the correct electron configuration for a neutral atom of magnesium (Mg, atomic number 12)?

Accepted Answer

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

Question 2

A sample contains two isotopes of chlorine: $$^{35}Cl (75.78$$% abundance, mass = 34.969 amu) and $$^{37}Cl (24.22$$% abundance, mass = 36.966 amu). What is the average atomic mass of chlorine?

Accepted Answer

$$35.45\ 	ext{amu}$$

Question 3

Which of the following best describes a mixture?

Accepted Answer

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

Question 4

How much energy (in calories) is required to heat 50.0 g of water from $$20.0^\circ C to$$ $$80.0^\circ C$$? (Specific heat of water = $$1.00\ 	ext{cal/g}^\circ C)$$

Accepted Answer

$$3000\ 	ext{cal}$$

Question 5

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

Accepted Answer

Atomic radius increases down a group and decreases across a period.

Question 6

A food contains 9 grams of fat, 4 grams of protein, and 12 grams of carbohydrate. What is the total energy content in kilocalories? (Fat: 9 kcal/g, Protein: 4 kcal/g, Carbohydrate: 4 kcal/g)

Accepted Answer

$$125\ 	ext{kcal}$$

Question 7

Which of the following is the correct orbital diagram for oxygen (atomic number 8)?

Accepted Answer

$$1s\uparrow\downarrow\ 2s\uparrow\downarrow\ 2p\uparrow\downarrow\uparrow\uparrow$$

Question 8

Which of the following is a pure substance?

Accepted Answer

Distilled water

Question 9

How much heat (in joules) is required to melt 10.0 g of ice at $$0^\circ C$$? (Heat of fusion for water = $$334\ 	ext{J/g})$$

Accepted Answer

$$3340\ 	ext{J}$$

Question 10

Which of the following best describes scientific notation?

Accepted Answer

A way to express very large or very small numbers as a product of a number between 1 and 10 and a power of 10

Question 11

A heating curve shows the temperature of a substance as it is heated. What happens to the temperature during a phase change?

Accepted Answer

The temperature remains constant while the substance absorbs heat.

Question 12

Which equation would you use to solve for the final temperature when a known mass of a substance is heated with a known amount of energy?

Accepted Answer

$$q = m \cdot c \cdot (T_f - T_i)$$

Question 13

Which of the following is the correct scientific notation for 0.00056?

Accepted Answer

$$5.6 	imes 10$$^{-4}$$

Question 14

Which of the following elements has the highest electronegativity?

Accepted Answer

Fluorine

Question 15

A solution is prepared by dissolving 10 g of NaCl in 90 g of water. Which statement is correct?

Accepted Answer

The solution is a homogeneous mixture.

Question 16

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons

Question 17

If 100 g of water at $$100^\circ C is $$converted to steam at $$100^\circ C$$, how much energy is required? (Heat of vaporization for water = $$2260\ 	ext{J/g})$$

Accepted Answer

$$226,000\ 	ext{J}$$

GOB Chemistry Exam 1 Review Topics Guidance

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