Q: Convert 0.005 meters to micrometers using SI prefixes.

$$0.005 \times 10^6$ = 5000$$ \mu m

Q: What is the volume, in liters, of a cube with sides of 10 cm?

$$10 \times 10 \times 10 = 1000 cm$^3$$; $$1000 cm$^3 = 1 L$$

Q: If 0.500 g of magnesium oxide contains 0.455 g magnesium, what is the mass percentage of magnesium in magnesium oxide?

$$\frac{0.455}{0.500} \times 100 = 91.0\%$$

Question 1

Which of the following best describes a homogeneous mixture?

Accepted Answer

A mixture that is uniform throughout and can be separated by physical means.

Question 2

Which separation technique is most appropriate for separating a liquid from a dissolved solid, as shown in image (a)?

Accepted Answer

Filtration

Question 3

What is the SI base unit for mass?

Accepted Answer

kilogram (kg)

Question 4

Convert 0.005 meters to micrometers using SI prefixes.

Accepted Answer

$$0.005 	imes 10^6$ = 5000$$ \mu m

Question 5

A thermometer shows 100°C. What is this temperature in Kelvin?

Accepted Answer

$$100 + 273.15 = 373.15 K$$

Question 6

What is the volume, in liters, of a cube with sides of 10 cm?

Accepted Answer

$$10 	imes 10 	imes 10 = 1000 cm$^3$$; $$1000 cm$^3 = 1 L$$

Question 7

A seawater sample contains 3.5% sodium chloride by mass. If you have 75 g of seawater, how many grams of sodium chloride are present?

Accepted Answer

$$75 	imes 0.035 = 2.625 g$$

Question 8

According to the Law of Conservation of Mass, what is the total mass after a reaction if 0.455 g magnesium reacts with 2.315 g oxygen to produce magnesium oxide?

Accepted Answer

$$0.455 + 2.315 = 2.770 g$$

Question 9

If 0.500 g of magnesium oxide contains 0.455 g magnesium, what is the mass percentage of magnesium in magnesium oxide?

Accepted Answer

$$\frac{0.455}{0.500} 	imes 100 = 91.0\%$$

Question 10

Which experiment led to the discovery of the electron's charge and mass?

Accepted Answer

Millikan's oil drop experiment

Question 11

Which particle has a mass of $$1.6726 	imes 10$$^{-24}$$ g and a charge of +1.6022$$ 	imes $$10^{-19} C$$?

Accepted Answer

Proton

Question 12

How many moles are in 4.07 g of sulfur (atomic mass = 32.07 g/mol)?

Accepted Answer

$$\frac{4.07}{32.07} = 0.127$$ mol

Question 13

Which of the following statements about isotopes is correct?

Accepted Answer

Isotopes have the same atomic number but different mass numbers.

Question 14

What is the relationship between frequency ($$
u$$), wavelength ($$\lambda$$), and the speed of light ($$c$$)?

Accepted Answer

$$c = 
u \cdot \lambda$$

Question 15

According to the Bohr model, what happens when an electron falls from a higher energy orbit to a lower energy orbit?

Accepted Answer

The atom emits energy as a photon.

Question 16

Calculate the energy change ($$\Delta E) $$when an electron moves from $$n_i = 3 to$$ $$n_f = 2 in a $$hydrogen atom. Use $$R_H = 2.179 	imes 10$$^{-18}$$ J.

Accepted Answer

$$\Delta E = -R_H \left( \frac{1}{n_f^2$} - \frac{1}{n_i^2$} ight) = -2.179 	imes 10$$^{-18}$$ \left( \frac{1}{4} - \frac{1}{9} ight) = -2.179 	imes 10$$^{-18}$$ 	imes 0.139 = -3.03 	imes 10$$^{-19}$$ J

Question 17

Which quantum number determines the shape of an orbital?

Accepted Answer

Angular momentum quantum number ($$\ell)$$

Question 18

How many electrons can occupy a single orbital according to the Pauli exclusion principle?

Accepted Answer

Two, with opposite spins

Question 19

Which rule states that electrons occupy degenerate orbitals singly and with parallel spins before pairing up?

Accepted Answer

Hund's rule

Foundations of General Chemistry: Matter, Measurement, Atoms, and Electrons

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