Q: A 2.0 L sample of gas at 1.0 atm and 300 K is compressed to 1.0 L at constant temperature. What is the new pressure, according to Boyle’s Law?

New pressure = $$\frac{1.0 \times 2.0}{1.0} = 2.0$$ atm

Q: A reaction has a theoretical yield of 50.0 g, but only 40.0 g is obtained. What is the percent yield?

Percent yield = $$\frac{40.0}{50.0} \times 100 = 80\%$$

Question 1

Which of the following best describes the difference between a scientific theory and a scientific law?

Accepted Answer

A scientific theory provides an explanation for phenomena, while a law describes relationships that are consistently observed.

Question 2

A student measures the mass of a liquid as 25.0 g and its volume as 20.0 mL. What is the density of the liquid, and how should it be reported with correct significant figures?

Accepted Answer

Density = $$\frac{25.0}{20.0} = 1.25 g/mL$$

Question 3

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

Accepted Answer

Iron rusting in moist air

Question 4

Dalton’s Atomic Theory included several postulates. Which statement is NOT part of Dalton’s original theory?

Accepted Answer

Atoms of the same element can have different masses.

Question 5

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen by mass. What is the empirical formula of the compound?

Accepted Answer

CH$$_2O$$

Question 6

Which of the following best describes an electrolyte?

Accepted Answer

A substance that produces ions in solution and conducts electricity.

Question 7

A student mixes solutions of Na$$_2SO$_4$$ and BaCl$$_2. $$Which product will precipitate, and what is the net ionic equation?

Accepted Answer

BaSO$$_4$$ will precipitate; Net ionic equation: $$\mathrm{Ba$$^{2+}$$ (aq) + SO_4$^{2-} (aq) \rightarrow $$BaSO_4$$ (s)}$$

Question 8

What is the molarity of a solution prepared by dissolving 10.0 g of NaCl (molar mass = 58.44 g/mol) in enough water to make 250 mL of solution?

Accepted Answer

Molarity = $$\frac{10.0}{58.44} \div 0.250 = 0.684 M$$

Question 9

A 2.0 L sample of gas at 1.0 atm and 300 K is compressed to 1.0 L at constant temperature. What is the new pressure, according to Boyle’s Law?

Accepted Answer

New pressure = $$\frac{1.0 	imes 2.0}{1.0} = 2.0$$ atm

Question 10

Which statement about the kinetic-molecular theory of gases is correct?

Accepted Answer

Gas particles have negligible volume compared to the container.

Question 11

A reaction has a theoretical yield of 50.0 g, but only 40.0 g is obtained. What is the percent yield?

Accepted Answer

Percent yield = $$\frac{40.0}{50.0} 	imes 100 = 80\%$$

Question 12

Which of the following is a correct application of Hess’s Law?

Accepted Answer

The enthalpy change for a reaction is the sum of the enthalpy changes for individual steps.

Question 13

Which quantum number determines the shape of an atomic orbital?

Accepted Answer

Angular momentum quantum number ($$l)$$

Question 14

Which element has the highest first ionization energy among the following?

Accepted Answer

Neon (Ne)

Question 15

Which molecule is nonpolar despite having polar bonds?

Accepted Answer

CO$$_2$$

Question 16

What is the molecular geometry of SF$$_6$$ according to VSEPR theory?

Accepted Answer

Octahedral

Question 17

Which hybridization corresponds to a molecule with a trigonal planar geometry?

Accepted Answer

sp$$^2$$

Question 18

During an acid-base titration, a student uses 25.0 mL of 0.100 M HCl to neutralize 30.0 mL of NaOH. What is the concentration of the NaOH solution?

Accepted Answer

Concentration = $$\frac{0.100 	imes 25.0}{30.0} = 0.083 M$$

Question 19

Which statement about academic integrity in laboratory work is correct?

Accepted Answer

Falsifying laboratory results is considered academic misconduct.

CHEM 1210: General Chemistry I – Syllabus and Course Structure Study Guide

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