Q: When an electron in the 2p orbital of a lithium atom makes a transition to the 2s orbital, a photon of wavelength 670.8 nm is emitted. What is the energy difference between these 2p and 2s orbitals? Use $$E = \frac{hc}{\lambda}$$, where $$h = 6.626 \times 10$$^{-34}$$ \ \mathrm{J \cdot s}$$ and $$c = 3.00 \times 10^8$ \ \mathrm{m/s}.$$

$$2.96 \times 10$$^{-19}$$ \ \mathrm{J}$$

Q: It is believed that two carbon-12 nuclei can react in the core of a supergiant star to form sodium-23 and hydrogen-1. Calculate the energy released from this reaction for each mole of hydrogen formed. The masses of carbon-12, sodium-23, and hydrogen-1 are 12.0000 amu, 22.989767 amu, and 1.007825 amu, respectively. ($$^{12}_6C $$+ ^{12}$$_6C \$$rightarrow ^{23}$$_{11}Na + ^1$_1H$$; $$1\ \mathrm{amu} = 931.5\ \mathrm{MeV}$$, $$1\ \mathrm{MeV} = 1.602 \times 10$$^{-13}$$\ \mathrm{J})$$

$$2.16 \times 10$$^{8}$$ \ \mathrm{kJ}$$

Question 1

When an electron in the 2p orbital of a lithium atom makes a transition to the 2s orbital, a photon of wavelength 670.8 nm is emitted. What is the energy difference between these 2p and 2s orbitals? Use $$E = \frac{hc}{\lambda}$$, where $$h = 6.626 	imes 10$$^{-34}$$ \ \mathrm{J \cdot s}$$ and $$c = 3.00 	imes 10^8$ \ \mathrm{m/s}.$$

Accepted Answer

$$2.96 	imes 10$$^{-19}$$ \ \mathrm{J}$$

Question 2

Refer to the hydrogen atom energy-level diagram (see $$image_1). $$Which combination of transitions results in a net energy change of $$0 \ \mathrm{J}$$?

Accepted Answer

IV, II, and V

Question 3

Which of the following statements about atomic structure is true?

Accepted Answer

Ni has two unpaired electrons in its 3d orbitals.

Question 4

How many electrons in an atom can have the quantum numbers $$n = 3$$, $$l = 2$$?

Accepted Answer

10

Question 5

Which of the following factors influence the effective nuclear charge $$Z_{	ext{eff}} of a $$particular electron in an atom?

Accepted Answer

All of the above factors

Question 6

Which of the following orderings gives a correct trend in ionization energy?

Accepted Answer

I) $$Al \u003c Si \u003c P \u003c Cl$$; IV) $$Na^+ \u003c Mg$$^{2+}$$ \u003c Al$$^{3+}$$ \u003c Si$$^{4+}$$

Question 7

Which of the following series of elements would have most nearly the same atomic radius?

Accepted Answer

Sc, Ti, V, Cr

Question 8

Select the polar molecule among the following.

Accepted Answer

SF$$_4$$

Question 9

Which of the following molecules has a zero dipole moment?

Accepted Answer

PF$$_5$$

Question 10

The N$$_2$$ bond energy is 941 kJ/mol and the F$$_2$$ bond energy is 154 kJ/mol. If $$\frac{1}{2} N_2$(g) + \frac{3}{2} F_2$(g) \rightarrow NF_3$(g)$$, $$\Delta H^\circ = -103 kJ/$$mol, calculate the N–F bond energy.

Accepted Answer

268 kJ/mol

Question 11

Which of the following species has the largest number of lone pairs of electrons around the central atom?

Accepted Answer

XeF$$_2$$

Question 12

Which of the following molecules has a nonlinear structure?

Accepted Answer

O$$_3$$

Question 13

Which of the following molecules has a central atom that is $$sp^3$$ hybridized?

Accepted Answer

H$$_2S$$

Question 14

Which of the following polar compounds is likely to have the highest boiling point?

Accepted Answer

CH$$_3CH$_2OH$$

Question 15

Potassium chloride is used as a substitute for sodium chloride for individuals with high blood pressure. Identify the limiting reactant and determine the mass of the excess reactant remaining when 7.00 g of chlorine gas reacts with 5.00 g of potassium to form potassium chloride. ($$2K + Cl_2$ \rightarrow 2KCl)$$

Accepted Answer

Potassium is the limiting reactant; 2.47 g of chlorine remain.

Question 16

A system delivers 225 J of heat to the surroundings while delivering 645 J of work. Calculate the change in the internal energy, $$\Delta E$$, of the system. ($$\Delta E = q + w)$$

Accepted Answer

$$-420 \ \mathrm{J}$$

Question 17

Which of the following isotopes is definitely unstable?

Accepted Answer

$$^{204}_{84}\mathrm{Po}$$

Question 18

It is believed that two carbon-12 nuclei can react in the core of a supergiant star to form sodium-23 and hydrogen-1. Calculate the energy released from this reaction for each mole of hydrogen formed. The masses of carbon-12, sodium-23, and hydrogen-1 are 12.0000 amu, 22.989767 amu, and 1.007825 amu, respectively. ($$^{12}_6C $$+ ^{12}$$_6C \$$rightarrow ^{23}$$_{11}Na + ^1$_1H$$; $$1\ \mathrm{amu} = 931.5\ \mathrm{MeV}$$, $$1\ \mathrm{MeV} = 1.602 	imes 10$$^{-13}$$\ \mathrm{J})$$

Accepted Answer

$$2.16 	imes 10$$^{8}$$ \ \mathrm{kJ}$$

Question 19

Select the correct name for the following compound (see $$image_18).$$

Accepted Answer

4-ethyl-7-methyl-5-propyldecane

General Chemistry Exam 2 Study Guidance

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