Question 1

Air is best classified as

Accepted Answer

Air is a homogeneous mixture because it is composed of different gases (like nitrogen, oxygen, carbon dioxide, etc.) that are evenly distributed throughout.

Question 2

A marble tabletop is best classified as

Accepted Answer

A marble tabletop is a heterogeneous mixture because it consists of different minerals and components that are not uniformly distributed throughout the material.

Question 3

A pure substance that is composed of only one type of atom is best classified as

Accepted Answer

A pure substance that is composed of only one type of atom is an element.

Question 4

Which statement best describes N₂

Accepted Answer

N₂ is a molecule consisting of two nitrogen atoms bonded together, making it an element.

Question 5

A clear liquid is placed into a beaker and heated until it boils. After all of the liquid has evaporated, a white powder is found in the beaker. The original liquid is best classified as

Accepted Answer

The presence of a white powder after evaporation indicates that the original liquid contained dissolved substances, making it a homogeneous mixture.

Question 6

A red solid is heated in an evacuated container until it completely vaporizes. When the vapor cools, it is found to be a sliver liquid. The mass of the silver liquid is less than that of the original solid. The red solid is best classified as

Accepted Answer

The red solid is best classified as a compound because it changes its state and composition upon heating, indicating a chemical change. The mass loss suggests decomposition, which is characteristic of compounds rather than elements or mixtures.

Question 7

A sample of carotene is extracted from a carrot and found to contain 17.9 g of carbon and 2.1 g of hydrogen. A second carotene sample is synthesized in the lab and found to contain 10.0 g of carbon. How many grams of hydrogen are in the second sample?

Accepted Answer

The ratio of carbon to hydrogen in the first sample is 17.9 g C : 2.1 g H. To find the amount of hydrogen in the second sample, which contains 10.0 g of carbon, use the ratio: (2.1 g H / 17.9 g C) * 10.0 g C = 1.17 g H.

Question 8

Sodium chloride that is formed from a reaction of sodium vapor and chlorine gas is found to be 39.34% sodium by mass. A 4.86 g sample of sodium chloride that is purified from sea water contains how many grams of sodium?

Accepted Answer

The percentage of sodium in sodium chloride is 39.34%. Therefore, in a 4.86 g sample of sodium chloride, the mass of sodium is 4.86 g * 0.3934 = 1.91 g.

Question 9

Two elements X and Y combine to form two compounds with the following compositions $\begin{array}{|l|l|l|} \hline \text { Compound } & \% \text { Mass X} & \% \text { Mass Y} \ \hline & & \ \hline 1 & 22.56 & 77.44 \ \hline 2& 14.87 & 85.13 \ \hline \end{array}$ If compound 1 has the formula XY₃ then a possible formula for compound 2 is

Accepted Answer

The answer of Two elements X and Y combine to...

Question 10

A compound is found to be 40.62% Si and 59.94% N. A possible formula for this compound is

Accepted Answer

The ratio of Si to N is 40.62/28.09 : 59.94/14.01 = 1.447 : 4.277 = 1 : 3. Therefore, the possible formula is SiN3.

Question 11

You are trying to use percent mass of hydrogen to determine if a compound is epinephrine (C₉H₁₃NO₃) or nor-epinephrine (C₈H₁₁NO₃). What is the maximum error that is acceptable for your instrument in order to distinguish between these two compounds?

Accepted Answer

The percent mass of hydrogen in epinephrine is approximately 6.98%, while in nor-epinephrine it is approximately 6.92%. The difference is 0.06%, so the maximum acceptable error must be less than this difference, making 0.5% the only viable option.

Question 12

A 20.0 g a sample is composed of a mixture of Fe₂O₃ and Fe₃O₄. The mixture is found to contain 14.45 g of iron. What percent of the sample is Fe₂O₃?

Accepted Answer

The answer of A 20.0 g a sample is composed...

Question 13

In the presence of a catalyst carbon monoxide (CO) will reaction with oxygen (O₂) to form carbon dioxide (CO₂). How many liters of carbon dioxide can be formed from 1.5 L of carbon monoxide (with excess oxygen) if all the gases are held at the same temperature and pressure?

Accepted Answer

According to the balanced chemical equation for the reaction CO + 1/2 O2 → CO2, one mole of CO reacts with one mole of O2 to produce one mole of CO2. Therefore, 1.5 L of CO will produce 1.5 L of CO2 under the same conditions of temperature and pressure.

Question 14

Gibbsite is an aluminum ore that is composed of 34.59% Al, 3.88% H, and 61.53% O. How much aluminum can be refined from 248.0 g of Gibbsite?

Accepted Answer

To find the amount of aluminum that can be refined from 248.0 g of Gibbsite, calculate 34.59% of 248.0 g. This results in 85.78 g of aluminum.

Question 15

1.28 g of pure gold reacts with chlorine gas to produce 1.97 g of a red solid. A possible formula for the red solid is?

Accepted Answer

The answer of 1.28 g of pure gold reacts with...

Question 16

Methane gas (CH₄) reacts with oxygen (O₂) to produce water vapor and carbon dioxide. What volume of water (H₂O) and carbon dioxide (CO₂) will be formed from the complete reaction of 3 L of methane with oxygen if all the gases are held at the same temperature and pressure?

Accepted Answer

According to the balanced chemical equation CH₄ + 2O₂ → CO₂ + 2H₂O, 1 mole of CH₄ produces 1 mole of CO₂ and 2 moles of H₂O. Therefore, 3 L of CH₄ will produce 3 L of CO₂ and 6 L of H₂O under the same conditions of temperature and pressure.

Question 17

The element zinc has two naturally occurring isotopes. The natural abundances and isotopic masses are

$\begin{array}{|l|l|l|}
\hline \text { Isotope } & \% \text { Abundance } & \text { Isotopic Mass } \
\hline & & \
\hline { }^{113} \mathrm{Zn}& 4.29 & 112.904 \
\hline { }^{115} \mathrm{Zn}& 95.71 & 114.904 \
\hline
\end{array}$
 
The atomic mass of naturally occurring zinc is

Accepted Answer

The answer of The element zinc has two naturally occurring...

Question 18

The element antinomy has two naturally occurring isotopes. The natural abundances and isotopic masses are

$\begin{array}{|l|l|l|}
\hline \text { Isotope } & \% \text { Abundance } & \text { Isotopic Mass } \
\hline & & \
\hline { }^{121} \mathrm{Sb}& 57.21& 120.904 \
\hline { }^{123} \mathrm{Sb}& 42.79 & 120.904 \
\hline
\end{array}$
 
The atomic mass of naturally occurring antinomy is

Accepted Answer

The atomic mass of an element is the weighted average of the masses of its isotopes, taking into account their relative abundances. The atomic mass of antimony can be calculated as follows:Atomic mass = (abundance of isotope 1 x mass of isotope 1) + (abundance of isotope 2 x mass of isotope 2)Atomic mass = (0.5721 x 120.904) + (0.4279 x 122.904)= 121.760

Question 19

How many neutrons are in a nucleus of a ²³⁵U atom?

Accepted Answer

The number of neutrons in an atom is calculated by subtracting the atomic number (number of protons) from the mass number. Uranium-235 has an atomic number of 92, so it has 235 - 92 = 143 neutrons.

Question 20

Which has the greatest number of neutrons?

Accepted Answer

The answer of Which has the greatest number of neutrons?
...

Quiz 1: The Atom in Modern Chemistry

Air is best classified as

A marble tabletop is best classified as

A pure substance that is composed of only one type of atom is best classified as

Which statement best describes N₂

A clear liquid is placed into a beaker and heated until it boils. After all of the liquid has evaporated, a white powder is found in the beaker. The original liquid is best classified as

A red solid is heated in an evacuated container until it completely vaporizes. When the vapor cools, it is found to be a sliver liquid. The mass of the silver liquid is less than that of the original solid. The red solid is best classified as

A sample of carotene is extracted from a carrot and found to contain 17.9 g of carbon and 2.1 g of hydrogen. A second carotene sample is synthesized in the lab and found to contain 10.0 g of carbon. How many grams of hydrogen are in the second sample?

Sodium chloride that is formed from a reaction of sodium vapor and chlorine gas is found to be 39.34% sodium by mass. A 4.86 g sample of sodium chloride that is purified from sea water contains how many grams of sodium?

A compound is found to be 40.62% Si and 59.94% N. A possible formula for this compound is

You are trying to use percent mass of hydrogen to determine if a compound is epinephrine (C₉H₁₃NO₃) or nor-epinephrine (C₈H₁₁NO₃) . What is the maximum error that is acceptable for your instrument in order to distinguish between these two compounds?

A 20.0 g a sample is composed of a mixture of Fe₂O₃ and Fe₃O₄. The mixture is found to contain 14.45 g of iron. What percent of the sample is Fe₂O₃?

In the presence of a catalyst carbon monoxide (CO) will reaction with oxygen (O₂) to form carbon dioxide (CO₂) . How many liters of carbon dioxide can be formed from 1.5 L of carbon monoxide (with excess oxygen) if all the gases are held at the same temperature and pressure?

Gibbsite is an aluminum ore that is composed of 34.59% Al, 3.88% H, and 61.53% O. How much aluminum can be refined from 248.0 g of Gibbsite?

1.28 g of pure gold reacts with chlorine gas to produce 1.97 g of a red solid. A possible formula for the red solid is?

Methane gas (CH₄) reacts with oxygen (O₂) to produce water vapor and carbon dioxide. What volume of water (H₂O) and carbon dioxide (CO₂) will be formed from the complete reaction of 3 L of methane with oxygen if all the gases are held at the same temperature and pressure?

How many neutrons are in a nucleus of a ²³⁵U atom?

Which has the greatest number of neutrons?

Quiz 1: The Atom in Modern Chemistry

Air is best classified as

A marble tabletop is best classified as

A pure substance that is composed of only one type of atom is best classified as

Which statement best describes N2

A clear liquid is placed into a beaker and heated until it boils. After all of the liquid has evaporated, a white powder is found in the beaker. The original liquid is best classified as

A red solid is heated in an evacuated container until it completely vaporizes. When the vapor cools, it is found to be a sliver liquid. The mass of the silver liquid is less than that of the original solid. The red solid is best classified as

A sample of carotene is extracted from a carrot and found to contain 17.9 g of carbon and 2.1 g of hydrogen. A second carotene sample is synthesized in the lab and found to contain 10.0 g of carbon. How many grams of hydrogen are in the second sample?

Sodium chloride that is formed from a reaction of sodium vapor and chlorine gas is found to be 39.34% sodium by mass. A 4.86 g sample of sodium chloride that is purified from sea water contains how many grams of sodium?

A compound is found to be 40.62% Si and 59.94% N. A possible formula for this compound is

You are trying to use percent mass of hydrogen to determine if a compound is epinephrine (C9H13NO3) or nor-epinephrine (C8H11NO3) . What is the maximum error that is acceptable for your instrument in order to distinguish between these two compounds?

A 20.0 g a sample is composed of a mixture of Fe2O3 and Fe3O4. The mixture is found to contain 14.45 g of iron. What percent of the sample is Fe2O3?

In the presence of a catalyst carbon monoxide (CO) will reaction with oxygen (O2) to form carbon dioxide (CO2) . How many liters of carbon dioxide can be formed from 1.5 L of carbon monoxide (with excess oxygen) if all the gases are held at the same temperature and pressure?

Gibbsite is an aluminum ore that is composed of 34.59% Al, 3.88% H, and 61.53% O. How much aluminum can be refined from 248.0 g of Gibbsite?

1.28 g of pure gold reacts with chlorine gas to produce 1.97 g of a red solid. A possible formula for the red solid is?

Methane gas (CH4) reacts with oxygen (O2) to produce water vapor and carbon dioxide. What volume of water (H2O) and carbon dioxide (CO2) will be formed from the complete reaction of 3 L of methane with oxygen if all the gases are held at the same temperature and pressure?

How many neutrons are in a nucleus of a 235U atom?

Which has the greatest number of neutrons?

Which statement best describes N₂

You are trying to use percent mass of hydrogen to determine if a compound is epinephrine (C₉H₁₃NO₃) or nor-epinephrine (C₈H₁₁NO₃) . What is the maximum error that is acceptable for your instrument in order to distinguish between these two compounds?

A 20.0 g a sample is composed of a mixture of Fe₂O₃ and Fe₃O₄. The mixture is found to contain 14.45 g of iron. What percent of the sample is Fe₂O₃?

In the presence of a catalyst carbon monoxide (CO) will reaction with oxygen (O₂) to form carbon dioxide (CO₂) . How many liters of carbon dioxide can be formed from 1.5 L of carbon monoxide (with excess oxygen) if all the gases are held at the same temperature and pressure?

Methane gas (CH₄) reacts with oxygen (O₂) to produce water vapor and carbon dioxide. What volume of water (H₂O) and carbon dioxide (CO₂) will be formed from the complete reaction of 3 L of methane with oxygen if all the gases are held at the same temperature and pressure?

How many neutrons are in a nucleus of a ²³⁵U atom?