Question 1

Which of the following best explains why sodium chloride (NaCl) conducts electricity when dissolved in water, but not as a solid?

Accepted Answer

In solid NaCl, ions are fixed in place and cannot move, but in aqueous solution, ions are free to move and carry charge.

Question 2

A student measures the mass of a sample as 2.50 g using a balance with a precision of 0.01 g. Which of the following recorded values is reported with the correct number of significant figures?

Accepted Answer

2.50 g

Question 3

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

Accepted Answer

Elements in the same group have similar chemical properties because they have the same number of valence electrons.

Question 4

A chemical reaction is carried out in a coffee-cup calorimeter. The temperature of the solution increases. Which of the following is true about the enthalpy change ($$\Delta H) $$for the reaction?

Accepted Answer

$$\Delta H is $$negative because the reaction is exothermic.

Question 5

Which of the following best describes the difference between an ionic and a covalent bond?

Accepted Answer

An ionic bond involves the transfer of electrons from one atom to another, while a covalent bond involves the sharing of electrons between atoms.

Question 6

A sample contains 0.250 mol of glucose ($$C_6H_{12}O_6$). What is the mass of this sample? (Molar mass of C_6H$$_{12}$$O_6 = 180.16 g/$$mol)

Accepted Answer

$$72.5\ \mathrm{g}$$

Question 7

Which of the following is the correct electron configuration for a neutral atom of phosphorus ($$Z=15$$)?

Accepted Answer

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

Question 8

A solution is prepared by dissolving 5.00 g of NaCl in enough water to make 250.0 mL of solution. What is the molarity of the solution? (Molar mass of NaCl = 58.44 g/mol)

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 9

Which of the following best explains why water ($$H_2O) $$has a bent molecular geometry?

Accepted Answer

The two lone pairs on the oxygen atom repel the hydrogen atoms, resulting in a bent shape according to VSEPR theory.

Question 10

Which of the following is a correct application of the law of conservation of mass to a chemical reaction?

Accepted Answer

The total mass of reactants equals the total mass of products in a chemical reaction.

Question 11

Which of the following best describes a redox (oxidation-reduction) reaction?

Accepted Answer

A reaction in which electrons are transferred from one species to another.

Question 12

A 10.0 g sample of calcium carbonate ($$CaCO_3) is $$heated, producing calcium oxide ($$CaO) $$and carbon dioxide ($$CO_2) $$according to the equation: $$CaCO_3(s$$) \rightarrow CaO(s) + $$CO_2(g$$)$$. What is the theoretical yield of CO_2$ in grams? (Molar mass: $$CaCO_3$$ = 100.09\ \mathrm{g/mol}$$, $$CO_2 = 44.01$$\ \mathrm{g/mol}$$)

Accepted Answer

$$4.40\ \mathrm{g}$$

Question 13

Which of the following statements about atomic structure is correct?

Accepted Answer

Electrons occupy discrete energy levels, and transitions between these levels involve absorption or emission of specific amounts of energy.

Question 14

Which of the following is the correct balanced chemical equation for the reaction of aluminum with oxygen to form aluminum oxide?

Accepted Answer

$$4Al(s) + 3O_2(g) \rightarrow 2Al_2O_3(s)$$

Question 15

Which of the following best explains why carbon dioxide ($$CO_2) is a $$nonpolar molecule, even though it contains polar bonds?

Accepted Answer

The linear geometry of $$CO_2$$ causes the bond dipoles to cancel each other out.

Question 16

A 25.0 mL sample of 0.200 M $$HCl is $$neutralized by 0.100 M $$NaOH. $$What volume of $$NaOH$$ solution is required? (Assume the reaction is $$HCl + NaOH \rightarrow NaCl + H_2O)$$

Accepted Answer

$$50.0\ \mathrm{mL}$$

Question 17

Which of the following is a correct statement about effective nuclear charge ($$Z_{\mathrm{eff}}) as $$you move across a period in the periodic table?

Accepted Answer

$$Z_{\mathrm{eff}}$$ increases because the number of protons increases while shielding remains relatively constant.

Question 18

Which of the following is the empirical formula for a compound containing 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass?

Accepted Answer

$$CH_2O$$

Question 19

Which of the following best describes the main idea behind Hess's Law?

Accepted Answer

The enthalpy change for a reaction is the same, regardless of the number of steps or the pathway taken.

CHY 121: General Chemistry I – Syllabus and Course Structure Study Guide

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