The land around a once active coal mine remains barren because empty coal mines are flooded with acid rain, so no life forms can survive. The correct option is a.
What is a coal mine?Coal mines are the places where coal is extracted from. Mines are the place where abundant minerals are present. These minerals are extracted from these places to use the minerals as fuel, making other metals and things. The three types of coal mines are long wall mining, retreat mining, and room-and-pillar mining.
Mines are places that are dig or excavated to very deep, so the topsoil goes into the valleys hence no nutrients in the soil, no plants, and no life.
Thus, the correct option is a.) Empty coal mines are flooded with acid rain, so no life forms can survive.
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Which of the following elements can have an expanded octet when they form covalent compounds with other elements?
A. lodine and chlorine
B. Sulfur and phosphorous
C. Nitrogen and boron
D. Sulfur and nitrogen
Answer:
B.
Explanation:
Some of the elements of the third-period and periods below can have expanded octet because they have d- sub-level.
We have 2 possible answers. A and B. Because lodine and chlorine. Sulfur and phosphorous are in the 3d or lower periods.
In the compound P2S5, where P forms 5 bonds.
Iodine and chlorine do not have enough difference in electronegativity to form compound ICl7.
So, the answer is B.
The elements sulphur and phosphorous can form expanded octet in some compounds especially in polyatomic compounds. Hence, option B is correct.
What is octet rule ?Octet rule states that, as the atoms achieve 8 electrons in their valence shell. As per this rule, atoms loss or gain electrons to attain octet and becomes stable.
Atoms with extra electrons such as metals will loss electrons through ionic bonding to attain octet. Whereas, non-metals with electron deficiency will gain electron through ionic or covalent bonding.
In some covalent compounds, the central atom may expand from octet. For example in SF₆ the central atom sulfur have 12 valence electrons surrounding it including those 6 electrons shared from F.
Similarly in PCl₅, there are 10 electrons surrounding the phosphorous atom. Therefore, option B is correct.
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crossover formula of potassium oxide.
Answer:
K2O
Explanation:
It carries the chemical formula K2O. Potassium cannot be found free because it is too reactive. It has valency +1 and combines readily with oxygen atoms forming K2O.
hope it helps
Convert the pressure 191.2 torr to kPa.
Select one:
Oa 25.5
Ob. 1430
c. 3.60
Od. 191
Answer:
25.5
Explanation:
divide the pressure value by 7.501 to get the answer oa. 25.5
Butane reacts with chlorine to form 2 isomers. Name these 2 isomers.
Explanation:
There are two isomers from the chlorination of the 'linear' butane, i.e. and there are two more isomers from the chlorination of isobutane (IUPAC 2-methyl-propane), i.e. These 4 are all the possible isomers of chlorobutane.
Question 22
3 pts
To what volume will a 2.33 L sample of gas expand if it is heated from 10.0°C to 100.0°C?
0.233L
4.41L
23.3 L
3.76 L
3.07 L
Answer:
3.07L
Explanation:
Charles law, which describes the direct relationship of the absolute temperature to its volume when the pressure is kept constant will be used in this case. The Charles' law equation is:
V1/T1 = V2/T2
Where; V1 is the volume of the gas at an initial state= 2.33L
V2 is the volume of the gas at a final state= ?
T1 is the absolute temperature of the gas at an initial state= 10°C
T2 is the absolute temperature of the gas at a final state= 100°C
The temperature in degree Centigrade (°C) must be converted to the absolute temperature unit (Kelvin) using:
T(K) = T(°C) + 273.15
T1 = 10°C + 273.15 = 283.15K
T2 = 100°C + 273.15 = 373.15K
To solve for V2 in the above Charles law equation, we make V2 the subject of the formula by saying:
V2 = V1 × T2 / T1
V2 = 2.33 × 373.15 / 283.15
V2 = 869.4395/ 283.15
V2 = 3.0705
Hence, the gas will be expanded to a volume of 3.07L when heated from 10.0°C to 100.0°C.
Which of these is an example of how engineers have contributed to society?
A. Our current understanding of viruses
B. The theoretical mathematics describing the orbits of planets
around the sun
C. The seven-mile bridge that spans across the Gulf of Mexico to
connect two cities of the Florida Keys
D. Nomadic tribes traveling in search of food to hunt and gather
A teacher wants to perform a classroom demonstration that illustrates both chemical and physical changes. Which
would be the best demonstration that she could use?
O bending a piece of aluminum
O breaking a matchstick
O dissolving sugar in water
O burning a candle
Mark this and return
Save and Exit
Next
Subrnit
Answer:
d. burning a candle
Explanation:
edge 2021
(:
Based on the electron configuration of the two
atoms, predict the ratio of metal cationic (+) atom
to nonmetal anionic (-) atom in the compound.
Lithium 1s²2s1
Nitrogen 1s22s22p3
Answer:
3:1
Explanation:
Lithium is a group 1 element. This means it would donate one electron to form the cation.
Nitrogen on the other hand is a group 5 element. It would accept 3 electrons to form the anion.
This means there has to be three lithium atoms, each donating an electron each to the nitrogen atom for a compound to be formed.
The formular for the ionic compound would be given as;
Li₃N
Hence the ration is 3:1
37.2 liters of a gas has a pressure of 362.43 kPa at 46.5 °C. If the pressure increases to
693.9 kPa and the temperature to 149.2 °C, what would be the new volume of the gas?
Select one:
Oa. 25.7
Ob. 62.3
Oc. 54
O d. 25.672
Answer:
Option A. 25.7 L.
Explanation:
Step 1:
Data obtained from the question. This include the following:
Initial volume (V1) = 37.2 L
Initial pressure (P1) = 362.43 kPa
Initial temperature (T1) = 46.5 °C
Final pressure (P2) = 693.9 kPa
Final temperature (T2) = 149.2 °C
Final volume (V2) =.?
Step 2:
Conversion of celsius temperature to Kelvin temperature.
This can be achieved as shown below:
Temperature (K) = Temperature (°C) + 273
T (K) = T (°C) + 273
Initial temperature (T1) = 46.5 °C
Initial temperature (T1) = 46.5 °C + 273 = 319.5 K.
Final temperature (T2) = 149.2 °C
Final temperature (T2) = 149.2 °C + 273 = 422.2 K.
Step 3:
Determination of the new volume.
This can be obtained by using the general gas equation as shown below:
Initial volume (V1) = 37.2 L
Initial pressure (P1) = 362.43 kPa
Initial temperature (T1) = 319.5 K
Final pressure (P2) = 693.9 kPa
Final temperature (T2) = 422.2 K
Final volume (V2) =.?
P1V1/T1 = P2V2/T2
362.43×37.2/319.5 = 693.9 × V2/422.2
Cross multiply
319.5×693.9×V2 = 362.43×37.2×422.2
Divide both side by 319.5 × 693.9
V2 = (362.43×37.2×422.2)/(319.5×693.9)
V2 = 25.7 L
Therefore, the new volume is 25.7 L.
The volume of a gas is 8.0 L at 9.9°C and {P3} atm. What volume will the gas occupy if the
temperature is raised to 9.3°C at constant pressure?
Select one:
O a. 7.98
Ob.0.263
C. 8.02
O d. 228
Answer:
Option A. 7.98 L.
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 8 L
Initial temperature (T1) = 9.9 °C
Final temperature (T2) = 9.3 °C
Final volume (V2) =..?
Next, we shall convert celsius temperature to Kelvin temperature. This can be achieved as shown below:
Temperature (K) = temperature (°C) + 273
T(K) = T (°C) + 273
Initial temperature (T1) = 9.9 °C
Initial temperature (T1) = 9.9 °C + 273 = 282.9 K
Final temperature (T2) = 9.3 °C
Final temperature (T2) = 9.3 °C + 273 = 282.3 K
Finally, we shall determine the new volume of the gas as follow:
Initial volume (V1) = 8 L
Initial temperature (T1) = 282.9 K
Final temperature (T2) = 282.3 K
Final volume (V2) =..?
V1/T1 = V2/T2
8/282.9 = V2/282.3
Cross multiply
282.9 x V2 = 8 x 282.3
Divide both side by 282.9
V2 = (8 x 282.3)/282.9
V2 = 7.98 L
Therefore, the new volume of the gas is 7.98 L
A sample of water is taken and kept in a beaker in a freezer at a constant temperature of 0°C. If the system is at dynamic equilibrium, which of these statements is true? The rate of freezing is equal to the rate of melting. The rate of freezing is greater than the rate of melting. The amount of ice is greater than the amount of water. The amount of ice is equal to the amount of water.
At dynamic equilibrium, the concentration of ice and water has been equal. Thus, option D is correct.
The equilibrium state can be given as the condition when the reactant and the product in the chemical reaction have been in equal amount.
In the condition when the water has bee kept in the freezer, the water will condense at the freezing temperature and will be converted to ice. The water there has been the reactant while the ice has been the product.
According to the law of equilibrium, at the equilibrium there has been equal concentration of reactant and products. Thus, at dynamic equilibrium, the concentration of ice and water has been equal. Thus, option D is correct.
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A gaseous substance turns directly into a solid. Which term describes this change?
O deposition
O evaporation
O melting
O sublimation
Answer:
deposition
Explanation:
Sublmation- solid transforming into a gas, skipping the liquid stage.
eveporation- a liquid transformimg into a gas
melting- a solid transforming into a liquid
deposition- the opposite of sublimation (your anwser)
A gaseous substance turns directly into a solid. The term which is indicative of this change is deposition.
Evaporation is a process in which a liquid which when exposed to heat boils and converted into vapors of water. For example, the water is converted into water vapors. Melting is a process in which the solid substance when exposed to heat melts . In this a solid is converted into liquid. For example, a solid ice is melted into liquid. Sublimation is a process in which a solid is converted into a vapor state without being converted into a liquid. For example, dry ice in which the solid dry ice is converted into vapors in presence of air. Deposition is the process in which gaseous molecules aggregate and combine to form a solid. It is opposite of sublimation process. For example, conversion of water vapors to ice.Hence, deposition is the correct option.
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A 223.6 mL of volume of gas is measured at 74.5C. If the pressure remains unchanged, what is the volume of gas at standard temperature? A) 1820 B) 61.02 C) 819.4 D) -307.5
Answer:
175.7 mL
Explanation:
The following data were obtained from the question:
Initial volume (V1) = 223.6 mL
Initial temperature (T1) = 74.5 °C
Final temperature (T2) = stp = 273 K
Final volume (V2) =.?
Next, we shall convert celsius temperature to Kelvin temperature.
This is illustrated below:
Temperature (K) = Temperature (°C) + 273
T (K) = T (°C) + 273
Initial temperature (T1) = 74.5 °C
Initial temperature (T1) = 74.5 °C + 273 = 347.5 K
Finally, we shall determine the volume of the gas at standard temperature as follow:
Initial volume (V1) = 223.6 mL
Initial temperature (T1) = 347.5 K
Final temperature (T2) = stp = 273 K
Final volume (V2) =.?
V1/T1 = V2/T2
223.6/347.5 = V2/273
Cross multiply
347.5 x V2 = 223.6 x 273
Divide both side by 347.5
V2 = (223.6 x 273) /347.5
V2 = 175.7 mL
Therefore, the volume of the gas at standard temperature is 175.7 mL.
What type of solid consists of positive metal cations surrounded by valence electrons that
are donated by the metal atoms and belong to the solid as a whole?
Select one:
O a. ionic
O b. covalent network
O c. metallic
O d. covalent molecular
Which of the following pollutants could be reduced through proper maintenance and area ventilation to improve human health?
Asbestos
Chimney soot
Formaldehyde
Natural pesticides
Answer:
Chimney soot
Explanation:
The periodicity of chimney used in homes is very highly harmful to human health. If proper maintenance and cleanliness and ventilation are taken care of on such organic compounds, it can also control human health. Carbon compounds form chimneys are highly harmful to human health if timber or coal-fired black chimney soot can be disposed of from time to time and with constant maintenance we can control pollution.Which of the following statements is true?
A Question Progress A
A. Factors that affect the reaction rate can increase the speed of a reaction but not the
yield.
O
B. None of these
C. Catalysts are important to industry to increase product yields
D. A reaction can be sped up by reducing the surface area of solid reactants.
Reset Selection
Answer:
c
Explanation: c
The statement that is true from the following is catalysts are important to the industry to increase product yields. The correct option is C.
What is a catalyst?Catalysts are substances that speed up or increase the rate of reaction. The biological catalysts are enzymes. Enzymes are made up of proteins, and they are used in the reaction to increase the yield in less time. Catalyst does not mix with the process and after the reaction.
There are many chemical catalysts like nickel and iron. These catalysts are used in chemical and manufacturing processes. They impact, accelerate, and promote the reaction to get different yields.
Thus, the correct option is C. Catalysts are significant to industry to increase product yields.
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which of the following is a characteristic of a weak acid? A. It does not conduct electricity in water B. It is not as dangerous as a strong acid C. It is less concentrated than a strong acid D. It does not dissociate completely in water
Answer:
A B C D (all of the above)
Explanation:
Weak acid do not have a much hydrogen ions when in liquids or aqueous solutions. Examples of weak acids include vinegar, citric acid (from oranges, lemons, etc)
6. The diagram shows the building blocks of a lipid molecule.
A. Determine the name of each type of molecule.
Molecule A:
Molecule B:
B.How many molecules of A normally combine with one molecule of B to form a single fat molecule?
Answer:
A) Molecule A: Fatty acid
Molecule B: Glycerol
B) 3 molecules of molecule A(fatty acid) normally combine with one molecule of B (glycerol) to form a single fat molecule
Explanation:
QUESTION A:
Fats/lipids are one of the four major biomolecules in living systems. They are polymers, and like any polymer, they are made up of monomeric units which serve as building blocks. In the case of fats/lipids, fatty acids and glycerol are the two major building blocks.
Fatty acids are biological compounds made up of a hydrocarbon chain with a terminal carboxyll group (-COOH), which confers its acidic properties upon it. Hence, based on the structural diagram of molecule A in the attached image, it can be observed that the functional group is a carboxyll group. Therefore, molecule A is a FATTY ACID.
Glycerol is a compound with more than one hydroxyll group (-OH) in its chemical structure. It has the chemical formula; C3H8O3 with three hydroxyll groups attached to each of the carbon atoms. Therefore, as observed in the image, molecule B is a GLYCEROL because it contains 3 hydroxyll groups.
QUESTION B:
In the chemical structure of a fat molecule, three fatty acids are attached to each of the three carbon atoms of the glycerol molecule. This is done through the process of esterification i.e. combination of carboxyll group with hydroxyll group. Due to the fact that it takes 3 molecules of fatty acids to combine with one molecule of glycerol, fats are referred to as triglycerides.
A solution has an [H+] or [H3O+] of 1.25 X 10-9. What is the [OH-]?
a.01.25 X 105
b.8.00 X 10-6
c.None are correct
d.0.875
e.1.25 X 10-23
n a covalent bond: A. Both atoms share their electrons. B. One atom accepts electrons from another. C. The atoms attract each other but their electrons do not interact. D. None of these.
Answer:
Hey there!
In a covalent bond, both atoms share their electrons.
Hope this helps :)
The correct statement is that in a covalent bond, both atoms share their electrons. The correct answer is A. Both atoms share their electrons.
In a covalent bond, both atoms share their electrons to achieve a more stable electron configuration. Covalent bonds occur between nonmetal atoms, and they involve the sharing of electron pairs between the participating atoms. This sharing allows both atoms to achieve a more complete octet (or duet for hydrogen) in their outermost energy level.
Unlike ionic bonds, where one atom transfers electrons to another, covalent bonds involve a mutual sharing of electrons. This sharing can be equal (nonpolar covalent) or unequal (polar covalent) depending on the electronegativity difference between the atoms involved.
Option B, "One atom accepts electrons from another," is not characteristic of a covalent bond. That description aligns more with an ionic bond, where one atom donates electrons to another, resulting in the formation of charged ions.
Option C, "The atoms attract each other but their electrons do not interact," does not accurately describe a covalent bond. In a covalent bond, the sharing of electrons is the basis of the interaction between atoms, and the electrons of both atoms do interact and participate in the bond formation.
Therefore, the correct statement is that in a covalent bond, both atoms share their electrons.
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In the redox reaction AgNO3 + Na → NaNO3 + Ag, which element has been
reduced?
The element that has been reduced in the redox reaction [tex]AgNO_3 + Na NaNO_3 + Ag[/tex] is silver (Ag). A redox (reduction-oxidation) reaction involves the reduction of one element by the gain of electrons and the oxidation of another element by the loss of electrons.
When sodium (Na) loses one electron to generate [tex]NaNO_3[/tex] in this reaction, sodium changes from its neutral state (with a zero oxidation number) to a positive oxidation state (+1). On the other hand, when silver (Ag) in AgNO3 gets one electron to create Ag, it moves from a +1 oxidation state to a neutral state (with zero oxidation number).
Silver is the element that undergoes reduction in this process because reduction entails a gain of electrons, reducing it from its +1 oxidation state to its neutral state.
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A 153.5 mL volume of gas is measured at 71.1°C. If the pressure remains unchanged,
what is the volume of the gas at standard temperature?
Select one:
O a. 1638
Ob. 39.98
O c. 589.4
Od.-207.6
Answer:
b
Explanation:
39.98, 153.5 mL volume of gas is measured at 71.1°C
2SO2(g) + O2(g) ⟶ 2SO3(g), △H = -198 kJ What is the enthalpy change that occurs when 58.0 g SO2 reacts with excess oxygen in the above reaction?
Answer:
Enthalpy change = -98.6kJ
Explanation:
Based on the reaction:
2SO₂(g) + O₂(g) ⟶ 2SO₃(g), △H = -198 kJ
When 2 moles of SO₂ (Molar mass: 64.066g/mol) reacts with 1 mole of oxygen, enthalpy change is -198kJ
To know enthalpy change of 58.0g of SO₂ with excess oxygen we need to calculate moles of SO₂ thus:
58.0g SO₂ ₓ (1mol / 64.066g) = 0.905 moles SO₂
If 2 moles of SO₂ produce an enthalpy change of -198kJ, 0.905 moles SO₂ will produce:
0.905 moles SO₂ ₓ (-198kJ / 2 moles SO₂) =
Enthalpy change = -98.6kJ
Given the reaction: N2(9) +2O2(g) = 2NO2(9) The forward reaction is
endothermic. Determine which of the following changes would result in more
product being produced.
I. Increase NO2
II. Decrease O2
III. Add a catalyst
IV. Increase the temperature
V. Increase the pressure
A. IV and V
B. I and 11
C. II and IV
D. II, III, and V
Reset Selection
Tartaric acid, C4H6O6, has the first ionization constant with the value: Ka1 = 9.20 × 10-4. Calculate the value of pKb for the conjugate base of tartaric acid. 10.963 3.036 1.087 x 10-11 9.20 x 10-4
Answer:
pKb = 10.96
Explanation:
Tartaric acid is a dyprotic acid. It reacts to water like this:
H₂Tart + H₂O ⇄ H₃O⁺ + HTart⁻ Ka1
HTart⁻ + H₂O ⇄ H₃O⁺ + Tart⁻² Ka2
When we anaylse the base, we have
Tart⁻² + H₂O ⇄ OH⁻ + HTart⁻ Kb1
HTart⁻ + H₂O ⇄ OH⁻ + H₂Tart Kb2
Remember that Ka1 . Kb2 = Kw, plus pKa1 + pKb2 = 14
Kb2 = Kw / Ka1 → 1×10⁻¹⁴ / 9.20×10⁻⁴ = 1.08×10⁻¹¹
so pKb = - log Kb2 → - log 1.08×10⁻¹¹ = 10.96
Attractive forces between molecules in a solid are
than bonds between atoms in a molecule.
A. stronger
B. the same as
C. weaker
D. much stronger
Answer:
A. stronger
Explanation:
Which metal can replace another metal in a reaction?
O A. A metal higher on the activity series list will replace one that is
lower.
B. A metal lower on the activity series list will replace one that is
higher
O c. Ametal on the activity series list will replace one that is not on the
list.
D. Any metal on the list can replace any other metal also on the list.
Answer:
O A. A metal higher on the activity series list will replace one that is
lower.
Answer:
A metal higher on the activity series list will replace one that is
lower.
Explanation:
For the reaction 2HNO3 + Mg(OH)2 + Mg(NO3)2 + 2H20, how many grams of magnesium
nitrate are produced from 17.37 mol of nitric acid, HNO3?
Select one:
O a. 1290
Ob. 859
O c. 5160
Od. 1080
Answer:
mass = (a) 1290
Explanation:
as 2 moles of nitric acid gives one mole of of magnesium nitrate . we should divide the number of moles of of nitric acid by 2 .
Then apply the formula:
number of moles= mass/molar ratio
thanks
The diagrams show the partides of a substance
Which statement best describes the process that the diagrams show?
O A solid loses fonetic energy to become a loud and then becomes a gas
O A solid sains kinetic energy to become a loud and then becomes a gas
O Asas loses tonerc energy to become a loud and then becomes a solid
O A gas as kinetic energy to become a loud and then becomes a solid
Answer:
B. A solid gains kinetic energy to become a liquid and then becomes a gas.
Given the equation: N2 +202->2NO2, what mass of oxygen is required to react completely
with 48.400 g of nitrogen?
Select one:
O a. 110.5
b. 76.0
O c. 96.76
Od. 214