Q: Which of the following is a correct conversion factor for converting between moles and number of particles?

$1 \text{ mol} = 6.022 \times 10^{23}$ \text{ particles}$

Question 1

Which experiment provided direct evidence for the existence of negatively charged particles within atoms, and what was the main observation?

Accepted Answer

Thomson's Cathode Ray Tube Experiment; observed the deflection of cathode rays toward a positively charged plate, indicating the presence of negatively charged particles.

Question 2

In Millikan's Oil Drop Experiment, the charge of the electron was determined to be $e = -1.602 	imes 10^{-19}$ C. If the mass of the electron is $m_e = 9.109 	imes 10^{-31}$ kg, what is the charge-to-mass ratio of the electron?

Accepted Answer

$1.76 	imes 10^{11}$ C/kg

Question 3

Which statement best describes the Plum-Pudding Model of the atom proposed by J.J. Thomson?

Accepted Answer

Electrons are distributed throughout a diffuse, positively charged sphere.

Question 4

Rutherford's Gold Foil Experiment led to which major revision of atomic theory?

Accepted Answer

Atoms contain a tiny, dense nucleus containing most of the mass and positive charge.

Question 5

Which of the following correctly describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 6

Given the nuclide symbol $^{22}_{10}\mathrm{Ne}$, how many neutrons does this isotope of neon have?

Accepted Answer

12

Question 7

Which group in the periodic table is known as the 'alkali metals'?

Accepted Answer

Group 1

Question 8

What is the average atomic mass of neon, given the following data: Neon-20 (19.9924 u, 90.4838%), Neon-21 (20.9940 u, 0.2696%), Neon-22 (21.9914 u, 9.2465%)?

Accepted Answer

$20.1799$ u

Question 9

A tablet contains 500 mg of calcium carbonate ($\mathrm{CaCO}_3$). What is the number of moles of $\mathrm{CaCO}_3$ in the tablet? (Molar mass of $\mathrm{CaCO}_3 = 100.09$ g/mol)

Accepted Answer

$5.00 	imes 10^{-3}$ mol$

Question 10

How many formula units of $\mathrm{CaCO}_3$ are present in a 500 mg tablet? (Molar mass $= 100.09$ g/mol, Avogadro's number $= 6.022 	imes 10^{23}$)

Accepted Answer

$3.01 	imes 10^{21}$

Question 11

Which of the following compounds is ionic?

Accepted Answer

$\mathrm{NaCl}$

Question 12

Calculate the formula mass of $\mathrm{CaCl}_2$ (Ca: 40.08 u, Cl: 35.45 u).

Accepted Answer

$110.98$ u

Question 13

How many molecules of $\mathrm{H}_2\mathrm{O}_2$ are in a 10 g sample? (Molar mass $= 34.02$ g/mol, Avogadro's number $= 6.022 	imes 10^{23}$)

Accepted Answer

$1.77 	imes 10^{23}$

Question 14

A sample contains $18.08$ g of $\mathrm{NO}_2$ (molar mass $= 46.01$ g/mol). How many moles of $\mathrm{NO}_2$ are present?

Accepted Answer

$0.393$ mol

Question 15

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

Accepted Answer

Elements in the same group have similar chemical properties.

Question 16

What is the molar mass of $\mathrm{SO}_3$? (S: 32.07 g/mol, O: 16.00 g/mol)

Accepted Answer

$80.07$ g/mol

Question 17

Which of the following best describes a molecule?

Accepted Answer

A combination of two or more atoms of the same or different elements, held together by chemical bonds in a fixed ratio.

Question 18

If a compound contains 2 moles of $\mathrm{NH}_3$, what is its mass in grams? (Molar mass $= 17.03$ g/mol)

Accepted Answer

$34.06$ g

Question 19

Which of the following is a correct conversion factor for converting between moles and number of particles?

Accepted Answer

$1 	ext{ mol} = 6.022 	imes 10^{23}$ 	ext{ particles}$

Atoms, Molecules, and Ions: Structure, Experiments, and the Periodic Table

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