Question 1

Which of the following elements is a Group 1 alkali metal located in the 3rd period of the periodic table?

Accepted Answer

Sodium

Question 2

A student has a 0.500 g sample of $$t-$$butyl alcohol ($$C_4H_{10}O). If $$the molar mass of $$t-$$butyl alcohol is $$74.1224 \ \mathrm{g/mol}$$, how many moles are present in the sample?

Accepted Answer

$$0.00675 \ \mathrm{mol}$$

Question 3

Which of the following best describes the Law of Constant Composition?

Accepted Answer

A chemical compound always contains the same proportion of elements by mass.

Question 4

Given the following reaction: $$3\mathrm{Mg}_3\mathrm{N}_2 + 6\mathrm{H}_2\mathrm{O} \rightarrow 3\mathrm{Mg}(\mathrm{OH})_2 + 2\mathrm{NH}_3$$, how many grams of $$\mathrm{Mg}(\mathrm{OH})_2 ($$molar mass $$58.3197 \ \mathrm{g/mol}) $$can be produced from $$0.100 \ \mathrm{g} of$$ $$\mathrm{Mg}_3\mathrm{N}_2 ($$molar mass $$100.928 \ \mathrm{g/mol}$$)?

Accepted Answer

$$0.173 \ \mathrm{g}$$

Question 5

A sample of Comol contains $$71\%$$ iron, $$12\%$$ cobalt, and $$17\%$$ holmium by mass. If a student obtains a $$250.0 \ \mathrm{g}$$ sample, how many grams of cobalt are present?

Accepted Answer

$$30.0 \ \mathrm{g}$$

Question 6

Which of the following is a correct balanced chemical equation for the reaction of magnesium nitride with water to produce magnesium hydroxide and ammonia?

Accepted Answer

$$\mathrm{Mg}_3\mathrm{N}_2 + 6\mathrm{H}_2\mathrm{O} \rightarrow 3\mathrm{Mg}(\mathrm{OH})_2 + 2\mathrm{NH}_3$$

Question 7

A $$250.0 \ \mathrm{g}$$ sample of Comol contains $$12\%$$ cobalt by mass. How many moles of cobalt atoms are present? (Molar mass of Co = $$58.933 \ \mathrm{g/mol})$$

Accepted Answer

$$0.509 \ \mathrm{mol}$$

Question 8

Rubidium has two naturally occurring isotopes: $$^{85}\mathrm{Rb} ($$atomic mass $$84.9117 u$$, abundance $$72.17\%) $$and $$^{87}\mathrm{Rb} ($$atomic mass $$86.9091 u$$, abundance $$27.83\%). $$What is the atomic weight of rubidium?

Accepted Answer

$$85.47 u$$

Question 9

Which of the following is a correct formula for an oxide of chromium with a formula weight of approximately $$100.0 \ \mathrm{amu}$$? (Atomic masses: Cr = $$51.9961$$, O = $$15.9994)$$

Accepted Answer

$$\mathrm{CrO}_3$$

Question 10

A $$10.0 \ \mathrm{mL}$$ sample of $$t-$$butyl alcohol has a density of $$0.810 \ \mathrm{g/mL}. $$What is the mass of the sample?

Accepted Answer

$$8.10 \ \mathrm{g}$$

Question 11

Which of the following elements is a noble gas at room temperature?

Accepted Answer

Neon

Question 12

A vinegar sample contains $$5.0\% by $$mass acetic acid ($$\mathrm{CH}_3\mathrm{COOH}). If $$the density of vinegar is $$1.00 \ \mathrm{g/mL}$$, what mass of acetic acid is present in $$100.0 \ \mathrm{mL} of $$vinegar?

Accepted Answer

$$5.0 \ \mathrm{g}$$

Question 13

The speed of sound at $$1000 \ \mathrm{m}$$ and standard pressure is $$336.43 \ \mathrm{m/s}. $$Convert this speed to miles per hour. ($$1 \ \mathrm{mile} = 1.609 \ \mathrm{km})$$

Accepted Answer

$$752.5 \ \mathrm{miles/hour}$$

Question 14

Which of the following is a metalloid?

Accepted Answer

Silicon

Question 15

How many hydrogen atoms are present in $$0.674 \ \mathrm{g} of$$ $$t-$$butyl alcohol ($$C_4H_{10}O$$)? (Molar mass $$= 74.1224 \ \mathrm{g/mol}$$, Avogadro's number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$5.48 	imes 10$$^{22}$$

Question 16

Which of the following is a correct statement about cobalt?

Accepted Answer

Cobalt is a good conductor of electricity.

Question 17

A $$250.0 \ \mathrm{g}$$ sample of Comol contains $$17\%$$ holmium by mass. How many holmium atoms are present? (Molar mass of Ho = $$164.930 \ \mathrm{g/mol}$$, Avogadro's number $$= 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.55 	imes 10$$^{23}$$

Question 18

Which of the following is a correct definition of a diatomic element?

Accepted Answer

An element that exists as molecules composed of two atoms.

Question 19

Which of the following is a correct statement about the oxidation number of sulfur in $$\mathrm{SO}_2$$?

Accepted Answer

$$+4$$

Question 20

A $$100.0 \ \mathrm{mL}$$ sample of vinegar contains $$5.0\%$$ acetic acid by mass. If the density of vinegar is $$1.00 \ \mathrm{g/mL}$$, how many moles of acetic acid ($$\mathrm{CH}_3\mathrm{COOH}$$, molar mass $$60.052 \ \mathrm{g/mol}) $$are present?

Accepted Answer

$$0.0833 \ \mathrm{mol}$$

General Chemistry: Atomic Structure, Periodic Table, Stoichiometry, and Dimensional Analysis

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