Q: A solution is prepared by mixing 100.0 mL of 0.200 M NaCl and 200.0 mL of 0.100 M KCl. What is the final concentration of chloride ions in the solution?

$$[Cl^-] = \frac{(0.200 \times 100.0) + (0.100 \times 200.0)}{300.0}$$

Q: What is the mass of CaCO\_3 (M = 100.1 g/mol) required to completely react with 250.0 mL of 0.200 M HCl according to the equation: $$\mathrm{$$CaCO_3$$(s) + 2HCl(aq) \rightarrow $$CaCl_2$$(aq) + H_2O(l) + CO_2$(g)}$$?

$$0.200 \times 0.250 \times \frac{1}{2} \times 100.1 = 2.50 g$$

Q: What is the wavelength of light with a frequency of $$6.00 \times 10$$^{14}$$\ \mathrm{s}^{-1}$$? (Speed of light $$c = 3.00 \times 10^8$\ \mathrm{m/s})$$

$$\lambda = \frac{c}{\nu} = \frac{3.00 \times 10^8$}{6.00 \times 10$$^{14}$$} = 5.00 \times 10$$^{-7}$$\ \mathrm{m}$$

Q: A beam of photons with frequency $$1 \times 10$$^{15}$$\ \mathrm{s}^{-1} is $$incident on a metal surface. What is the energy of each photon? ($$h = 6.626 \times 10$$^{-34}$$\ \mathrm{J\cdot s})$$

$$E = h \nu = 6.626 \times 10$$^{-34}$$ \times 1 \times 10$$^{15}$$ = 6.626 \times 10$$^{-19}$$\ \mathrm{J}$$

Question 1

Which of the following compounds is expected to be insoluble in water according to the solubility guidelines provided?

Accepted Answer

BaSO\_4

Question 2

A solution is prepared by mixing 100.0 mL of 0.200 M NaCl and 200.0 mL of 0.100 M KCl. What is the final concentration of chloride ions in the solution?

Accepted Answer

$$[Cl^-] = \frac{(0.200 	imes 100.0) + (0.100 	imes 200.0)}{300.0}$$

Question 3

Which of the following best explains why CaCO\_3 is only slightly soluble in water?

Accepted Answer

Because most carbonates are insoluble except those of alkali metals and NH\_4^+.

Question 4

What is the mass of CaCO\_3 (M = 100.1 g/mol) required to completely react with 250.0 mL of 0.200 M HCl according to the equation: $$\mathrm{$$CaCO_3$$(s) + 2HCl(aq) \rightarrow $$CaCl_2$$(aq) + H_2O(l) + CO_2$(g)}$$?

Accepted Answer

$$0.200 	imes 0.250 	imes \frac{1}{2} 	imes 100.1 = 2.50 g$$

Question 5

Which of the following statements about the photoelectric effect is correct?

Accepted Answer

Electrons are ejected only if the frequency of the incident light is above a threshold value.

Question 6

Which of the following electron configurations violates the Pauli exclusion principle?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^6$$\ (with\ two\ electrons\ in\ the\ same\ orbital\ with\ the\ same\ spin)$

Question 7

What is the wavelength of light with a frequency of $$6.00 	imes 10$$^{14}$$\ \mathrm{s}^{-1}$$? (Speed of light $$c = 3.00 	imes 10^8$\ \mathrm{m/s})$$

Accepted Answer

$$\lambda = \frac{c}{
u} = \frac{3.00 	imes 10^8$}{6.00 	imes 10$$^{14}$$} = 5.00 	imes 10$$^{-7}$$\ \mathrm{m}$$

Question 8

Which statement about quantum numbers is FALSE?

Accepted Answer

The spin quantum number $$m_s$$ can be $$+1 or$$ $$-1.$$

Question 9

A beam of photons with frequency $$1 	imes 10$$^{15}$$\ \mathrm{s}^{-1} is $$incident on a metal surface. What is the energy of each photon? ($$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s})$$

Accepted Answer

$$E = h 
u = 6.626 	imes 10$$^{-34}$$ 	imes 1 	imes 10$$^{15}$$ = 6.626 	imes 10$$^{-19}$$\ \mathrm{J}$$

Question 10

Which of the following best describes the emission spectrum of hydrogen?

Accepted Answer

It consists of discrete lines corresponding to specific energy transitions.

Question 11

Which of the following statements about electron spin is correct?

Accepted Answer

Electron spin is quantized and can have values of $$+\frac{1}{2} or$$ $$-\frac{1}{2}.$$

Question 12

Which of the following solutions contains the smallest number of chloride ions?

Accepted Answer

50 mL of 0.10 M AlCl\_3

Question 13

Which quantum number determines the shape of an orbital in a hydrogen atom?

Accepted Answer

Azimuthal quantum number $$l$$

Question 14

According to de Broglie, what is the wavelength of an electron moving at $$2.00 	imes 10^6$\ \mathrm{m/s}$$? ($$m_e = 9.109 	imes 10$$^{-31}$$\ \mathrm{kg}$$, $$h = 6.626 	imes 10$$^{-34}$$\ \mathrm{J\cdot s})$$

Accepted Answer

$$\lambda = \frac{h}{m v} = \frac{6.626 	imes 10$$^{-34}$$}{9.109 	imes 10$$^{-31}$$ 	imes 2.00 	imes 10^6$} = 3.63 	imes 10$$^{-10}$$\ \mathrm{m}$$

Question 15

Which of the following statements about the 2p orbital is correct?

Accepted Answer

There is zero probability of finding an electron in the nodal plane.

Question 16

Which of the following electron configurations violates Hund's rule?

Accepted Answer

$$1s^2$$\ $$2s^2$$\ $$2p^3$$\ (with\ paired\ electrons\ in\ one\ 2p\ orbital\ before\ all\ are\ singly\ occupied)$

Question 17

What volume of 1.50 M KOH solution is needed to completely neutralize 20.0 mL of 0.500 M phosphoric acid ($$\mathrm{H_3PO_4}$$)? $$\mathrm{H_3PO_4(aq) + 3KOH(aq) \rightarrow K_3PO_4(aq) + 3H_2O(l)}$$

Accepted Answer

$$V = \frac{20.0 	imes 0.500 	imes 3}{1.50} = 20.0 mL$$

Question 18

Which of the following statements about the emission spectra of sodium and potassium is correct?

Accepted Answer

They are different because each element has a unique set of energy levels.

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