Q: Which of the following is the correct expression for Graham's Law of Effusion?

$$\dfrac{\text{Rate}_1}{\text{Rate}_2} = \sqrt{\dfrac{M_2$}{M_1$}}$$

Question 1

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

Accepted Answer

An ionic bond involves the transfer of electrons from a metal to a nonmetal, while a covalent bond involves the sharing of electrons between two nonmetals.

Question 2

A sample of nitrogen gas occupies $$2.50\ \mathrm{L} at$$ $$25\ ^\circ\mathrm{C}$$ and $$1.00\ \mathrm{atm}. $$What will be its volume at $$50\ ^\circ\mathrm{C}$$ and $$2.00\ \mathrm{atm}$$? (Assume ideal gas behavior.)

Accepted Answer

$$1.37\ \mathrm{L}$$

Question 3

Which of the following elements has the highest first ionization energy?

Accepted Answer

Neon ($$\mathrm{Ne})$$

Question 4

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

Accepted Answer

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

Question 5

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

Accepted Answer

$$0.342\ \mathrm{M}$$

Question 6

Which of the following best explains why water has a higher boiling point than methane ($$\mathrm{CH_4$}$$)?

Accepted Answer

Water forms hydrogen bonds, which are stronger than the London dispersion forces in methane.

Question 7

Which of the following is a correct statement about the behavior of gases according to the kinetic molecular theory?

Accepted Answer

Gas particles are in constant, random motion and collisions between them are perfectly elastic.

Question 8

Which of the following compounds is insoluble in water?

Accepted Answer

$$\mathrm{AgCl}$$

Question 9

A reaction has $$\Delta H = -125\ \mathrm{kJ}$$ and $$\Delta S = +50\ \mathrm{J/K}. At $$what temperature (in $$\mathrm{K}) $$does the reaction change from spontaneous to nonspontaneous? ($$\Delta G = \Delta H - T\Delta S)$$

Accepted Answer

$$2500\ \mathrm{K}$$

Question 10

Which of the following best describes the effect of a catalyst on a chemical reaction?

Accepted Answer

A catalyst lowers the activation energy, increasing the reaction rate without being consumed.

Question 11

Which of the following is the correct balanced equation for the combustion of propane ($$\mathrm{C_3H_8}$$)?

Accepted Answer

$$\mathrm{C_3H_8} + 5\mathrm{O_2$} \rightarrow 3\mathrm{CO_2$} + 4\mathrm{H_2O}$$

Question 12

Which of the following statements about oxidation and reduction is correct?

Accepted Answer

Oxidation is the loss of electrons, and reduction is the gain of electrons.

Question 13

Which of the following molecules is nonpolar?

Accepted Answer

$$\mathrm{CO_2$}$$

Question 14

A $$10.0\ \mathrm{g}$$ sample of ice at $$0\ ^\circ\mathrm{C} is $$added to $$100.0\ \mathrm{g} of $$water at $$30.0\ ^\circ\mathrm{C}. $$What is the final temperature of the mixture? ($$\Delta H_{fus} = 334\ \mathrm{J/g}$$, $$c_{water} = 4.18\ \mathrm{J/g\cdot ^\circ C})$$

Accepted Answer

$$23.0\ ^\circ\mathrm{C}$$

Question 15

Which of the following best describes the molecular geometry of ammonia ($$\mathrm{NH_3$}) $$according to VSEPR theory?

Accepted Answer

Trigonal pyramidal

Question 16

Which of the following is the correct net ionic equation for the reaction between aqueous solutions of silver nitrate and sodium chloride?

Accepted Answer

$$\mathrm{Ag^+ (aq) + Cl^- (aq) \rightarrow AgCl (s)}$$

Question 17

Which of the following statements about effective nuclear charge ($$Z_{eff}) is $$correct?

Accepted Answer

$$Z_{eff}$$ increases across a period from left to right.

Question 18

Which of the following is the correct expression for Graham's Law of Effusion?

Accepted Answer

$$\dfrac{	ext{Rate}_1}{	ext{Rate}_2} = \sqrt{\dfrac{M_2$}{M_1$}}$$

Question 19

Which of the following is a correct statement about the relationship between pressure, volume, and temperature for an ideal gas?

Accepted Answer

$$PV = nRT$$

Question 20

Which of the following best explains why atomic radius decreases across a period from left to right?

Accepted Answer

The effective nuclear charge increases, pulling electrons closer to the nucleus.

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