according to the law of conservation of matter, the number of _____ is not changed by a chemical reaction

Answer:

1,329

Explanation:

3.125 × 10^8 atoms of calcium-41 and 4.6875 × 10^9 atoms of potassium-41.

Option D is correct

A rare and long-lived radioactive isotope of calcium is calcium-41 (41Ca).

# Given-

Half life = 1.03×10^5 years

- After 1.03×10^5 years (1 half life)

calcium-41 will be 50%

potassium-41 will be 50%

- After 2.06×10^5 years (2 half lives)

calcium-41 will be 25%

potassium-41 will be 75%

- After 3.09×10^5 years (3 half lives)

calcium-41 will be 12.5%

potassium-41 will be 87.5%

- After 4.12×10^5 years (4 half lives)

calcium-41 will be 6.25%

potassium-41 will be 93.75%

After 4.12×10^5 years,

Calcium-41  = 6.25/100 × 5 × 10^9  =  3.12×10^8 atoms

Potassium-41  = 93.75/100 × 5 × 10^9  =  4.69×10^9 atoms

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Answer

C: Photochemical smog contains secondary pollutants that form when sulfur dioxide and nitrogen oxide interact in the atmosphere.

Explanation

Photochemical smog is a mixture of pollutants that are formed when nitrogen oxides and volatile organic compounds react to sunlight, creating a brown haze above cities in the United States. It tends to occur more often in summer because that is when we have the most sunlight. Their low concentration causes irritation in the nose and throat and their high concentration causes headache, chest pain, cough, and difficulty in breathing.

Research more Respiration

Explanation:

c realsed from the galaxie

Answer:

C

Explanation:

A P E X

The mass percentage is an important method which is used to calculate the concentration of a solution. The amount of water needed to add in order to make 17.85 % NaCl solution is 230.1 g.

The mass percentage of a component in a solution is defined as the mass in grams of that component present per 100 g of the solution. The term mass percentage is denoted as w/w. It is used to calculate the concentration of a binary solution.

Mass percentage = Mass of the component in the solution / Total mass of solution × 100

17.85 = 50.0 / 50.0 + x × 100

0.1785 (50.0 + x) = 50.0

8.925 + 0.1785 x = 50.0

0.1785 x = 41.075

x = 230.1 g

Thus the amount of water added to make the solution is 230.1 g.

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The variable that is not conserved during the combustion reaction of propane as shown by the equation would be none of the above.

Recall that the law of conservation says that atom/matter/mass is conserved in the course of reactions, although forms might change.

The number of moles of each atom is conserved because both the reactant and product sides have equal numbers of each atom that make up the compounds.

Unless the reaction is not carried out in an isolated system, the mass should be conserved. In other words, the total mass of the reactants must be equal to the total mass of the products. If the system is not isolated, materials may be exchanged with the surroundings and this might make the mass not to be conserved.

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Balance the half-reactions to guarantee that the number of electrons transferred in both reactions is the same:

NO3- + 8H+ + 10e- N2 + 4H2O H2 2H+ + 2e- NO3- + 8H+ + 10e-

The next step is to figure out how many electrons are moved when 145 molecules of H2 are oxidized. We can see from the balanced equation for the H2 half-reaction that 1 molecule of H2 makes 2 electrons:

2H+ + 2e- → H2

As a result, 145 molecules of H2 will yield:

145 molecular units H2 has two protons per molecule. 290 electrons Equals H2

Finally, we can use the denitrification reaction balanced equation to calculate how many molecules of N2 are created for 290 electrons:

1 molecule of N2 is produced by 10 electrons.

Therefore, 1 molecule N2 290 electrons/10 electrons = 29 molecules N2

29 molecules of N2 gas will be created.

To answer the second query, we must balance the half-reactions:

SO42- + 8H+ + 8e- H2S + 4H2O CO2 + 8H+ + 8e- CH3COO- + 2H2O SO42- + 8H+ + 8e- H2S + 4H2O

The balanced formulae show that 8 electrons are transferred in both half-reactions. As a result, in order to oxidize 48 molecules of CH3COO-, 6 molecules of SO42- must be reduced:

There are 48 nuclei CH3COO- 8 electrons per atom 384 protons = CH3CO-

384 electrons (eight electrons per atom) 48 units of SO42- SO42-

As a result, 48 molecules of CH3COO- reduced to CO2 will yield:

six electrons 4 H2O/molecule SO42- 24 units of SO42- H2O

The answer is that 24 molecules of water will be created.

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Answer:

Explanation:Two pre-requisite skills needed for students to learn the process of writing balanced chemical and ionic equations are:

1. Understanding of the periodic table and elements: Students must have a solid foundation in the periodic table, including recognizing elements by their symbols and understanding their properties, groups, and electron configurations.

2. Knowledge of chemical bonding and compound formation: Students should be familiar with the different types of chemical bonds (ionic, covalent, and metallic) and know how to construct chemical formulas for compounds based on their component elements and valence electrons.

Answer:

48000

Explanation:

maths

Answer:

48000

Explanation:

(5x10^3) = 5 × 1000 = 5000

(4.3x10^4) = 4.3 × 10000 = 43000

5000 + 43000 = 48000

Answer:

A. The reaction shifts to the right (products) and the concentrations of I and H₂ decrease.

Explanation:

If gas is removed from the system at equilibrium, the system will try to compensate for the loss by shifting the reaction in a direction that produces more gas molecules. This is known as Le Chatelier's principle, which states that a system at equilibrium will respond to a disturbance by shifting in a way that minimizes the effect of the disturbance.

In this case, since gas is being removed from the system, the reaction will shift to the side that produces more gas molecules. Looking at the balanced equation, we can see that 2HI(g) has a greater number of gas molecules compared to H₂(g) and I₂(g). Therefore, the system will shift to the right (products) to produce more HI(g) and reestablish equilibrium.

Answer: .B. 13C NMR spectra display peaks for only carbons that bear hydrogen atoms.

Explanation:

The statements that are true about 13C NMR are:

A. In 13C proton-decoupled NMR spectra, all peaks are singlets.

C 13C NMR chemical shifts occur over a greater range than 1H NMR chemical shifts.

D. 13C NMR easily differentiates between the different hybridized carbons (sp3, sp2, and sp hybridized carbons).organic-chemistry

Therefore, the option that isn't true is option B. "13C NMR spectra display peaks for only carbons that bear hydrogen atoms". This is false because 13C NMR will show every peak in the spectrum and it doesn't matter if it's only carbons that bear hydrogen atoms as everything will be shown.

The de Broglie wavelength of a 300-g object moving at a velocity of 50 m/s  is  4×10³⁵ meters. Hence, option (B) is correct.

When studying quantum mechanics, the de Broglie wavelength is a key idea. De Broglie wavelength is the wavelength (λ) that is connected to an item in relation to its momentum and mass. Typically, a particle's momentum is inversely proportional to its de Broglie wavelength.

The de Broglie wavelength of a 300-g object moving at a velocity of 50 m/s  is = Planck constant/momentum

= 6.6 ×10⁻³⁴/(0.300×50) meter

= 4×10³⁵ meters.

The de Broglie wavelength of a 300-g object travelling at 50 m/s is 4*10^35 meters. As a result, option (B) is accurate.

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Transparent because you can see right through it

Answer:

Explanation:

The Carnot engine is a theoretical or conceptual heat engine that has a higher efficiency than any practical or theoretical heat engine working between the same temperature range. The theoretical efficiency of a Carnot engine is considered as the highest efficiency and no practical heat engines can operate at that efficiency. A Carnot engine draws heat energy, performs useful work and the leftover energy is released from the working substance. According to the second law of thermodynamics, there must be a temperature gradient between the heat energy drawing point and release point of the heat engine.

Answer:

c

Explanation:

Compose balanced molecule, gross ionic, as well as net ionic formulae for the interaction between sodium hydroxide plus nitric acid in aqueous solutions. The net ionic equation's coefficient sum is three.

Ammonium nitrate, a crucial component of fertilizers, is created using nitric acid. Additionally, it is used to oxidize materials and to make explosives like trinitrotoluene (TNT) as well as nitroglycerin.

The liquid leads to severe burns when it comes in contact with your eyes, which could cause lifelong damage and vision loss. The liquefied or concentrated vapor causes immediate, severe, and profound burns on the skin, while acidic solution result in deep ulcers and leave a brilliant yellow stain.

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The reactions that result in the emission of light involve the ruthenium label and tripropylamine (TPA), two electrochemically active molecules.

Thus, The electrode surface inside the measurement cell is where the reactions take place.

The ruthenium label is oxidized at the electrode surface as an electrical potential is applied, and TPA is oxidized into a radical cation that spontaneously loses a proton.

When the resultant TPA radical interacts with oxidized ruthenium, the ruthenium label enters an excited state and emits a photon (620 nm) before decaying. The ruthenium label is renewed and ready to carry out numerous light-generating cycles as it goes back to its ground state.

Thus, The reactions that result in the emission of light involve the ruthenium label and tripropylamine (TPA), two electrochemically active molecules.

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The sample with the largest number of oxygen atoms will be calcium perchlorate.

Since we are not looking at the number of moles, the mass of the compounds has no bearing on the number of atoms of oxygen.

Therefore, the compound with the largest number of oxygen atoms is calcium perchlorate.

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The heat of reaction : 50.6 kJ

Based on the principle of Hess's Law, the change in enthalpy of a reaction will be the same even though it is through several stages or ways

Reaction

N₂(g) + 2H₂(g) ⇒N₂H₄(l)

thermochemical data:

1. N₂H₄(l)+O₂(g)⇒N₂(g)+2H₂O(l)   ΔH=-622.2 kJ

2. H₂(g)+1/2O₂(g)⇒H₂O(l)  ΔH=-285.8 kJ

We arrange the position of the elements / compounds so that they correspond to the main reaction, and the enthalpy sign will also change

1. N₂(g)+H₂O(l) ⇒  N₂H₄(l)+O₂(g) ΔH=+622.2 kJ

2. H₂(g)+1/2O₂(g)⇒H₂O(l)  ΔH=-285.8 kJ x 2 ⇒

2H₂(g)+O₂(g)⇒2H₂O(l)  ΔH=-571.6 kJ

Add reaction 1 and reaction 2, and remove the same compound from different sides

1. N₂(g)+2H₂O(l) ⇒  N₂H₄(l)+O₂(g) ΔH=+622.2 kJ

2.2H₂(g)+O₂(g)⇒2H₂O(l)            ΔH=-571.6 kJ

-------------------------------------------------------------------- +

N₂(g) + 2H₂(g) ⇒N₂H₄(l)   ΔH=50.6 kJ

Answer: ≈ 13620g³m

Explanation:

A = m d

1Lb = 454g

1000g = 1kg

m = 120Lb × 454/1Lb ×1kg/1000g ≈ 1362Lb/25g kg

m = 10.0 mg / kg

A = m d

(1362kg) ( 10.0 mg/kg)

≈ 13620g³m

Answer:

a) Heat energy is absorbed.

Explanation:

What occurs in endothermic reactions?

a) Heat energy is absorbed. YES. This is the definition of an endothermic reaction.

b) Water is produced. NO. Endothermic refers to the heat absorbed and not to the products formed.

c) Oxygen is produced. NO. Endothermic refers to the heat absorbed and not to the products formed.

d) Heat energy is released. NO. This is known as an exothermic reaction.

Answer:

B. Diethyl ether, dichloromethane, ethyl acetate, ethanol

Explanation:

The polarity of solvents can be determined by their polarity indexes. Polarity index is defined as the measure of the ability of the solvent to interact with various polar test solutes.

Diethyl ether is the least polar with a polarity index of 2.8

Dichloromethane with a polarity index of  3.1

Ethyl acetate with a polarity index of 4.3

Ethanol is the most polar with a polarity index of 5.2

The differences in polarities of these solvents is due to their structure. Polar solvents have large dipole moments because they contain bonds between atoms with very different electronegativities, such as oxygen and hydrogen.

Because of the two non-polar methyl groups in diethyl ether, it is not as polar as dichloromethane which has two electronegative chlorine atoms attached to a carbon atom. Similarly too, because diethyl ether has two  strongly electronegative oxygen atoms sharing a bond with carbon, it has a larger dipole moment than dichloromethane. Ethanol has an oxygen hydrogen bond which has the largest dipole moment, thus, it is the most polar of the given solvents.

Answer:

I'm pretty sure you have the correct answers

14. B

15. C

Explanation:

14. Sugar is soluble in water so when something soluble dissolves in water it naturally mixes together so C and D are obviously incorrect because the molecules are separated, and A doesn't look right either because the sugar particles have been pushed to the edge of the container. It looks best blended in B.

15. For a substance to be liquid at 100° C, the melting point has to be lower than 100°C and the boiling point has to be higher. C is the only option where 100 is in between the two values.

Answer:

A chemical reaction is occurring and energy is released.

Explanation:

Heat is released when you combine a strong acid with water, considered exothermic. That's why it's extremely important to add the acid to a large volume of water; not vice versa.

When water and sulfuric acid are mixed together at room temperature the exothermic reaction occurs and energy is released during the chemical reaction. Therefore, option (B) is correct.

An exothermic process can be explained as a thermodynamic process or reaction that liberates energy from the system to its surroundings, generally in the form of heat, light, or sound.

While an endothermic process is an inverse of an exothermic process where the energy absorbs in the form of heat. In the chemistry of chemical reactions, the bond energy is changed into thermal energy during the bond formation.

The energy that is liberated by the reaction happens in the form of the kinetic energy of molecules. The transition of electrons from one energy level to another energy level released energy.

The mixing of water and strong acid such as sulfuric acid release a large amount of energy which even causes the splash of the mixture. Therefore, we avoid adding water to acid instead of we dilute the acid by adding acid to water.

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Answer:

C. Because my teacher said so

Hope this helps :)

Answer:

Because my teacher said so

Explanation:

You good? lol

Answer:

The correct answer is -

(a) spontaneous;

(b) nonspontaneous;

(c) spontaneous;

(d) nonspontaneous;

(e) spontaneous;

(f) spontaneous

Explanation:

(a) Liquid water freezing at a temperature below its freezing point.

in this reaction, there is no requirement of external energy or force to make it possible due to the fact that the temperature of the environment is less than the freezing point of water. So, the water will spontaneously freeze.

(b) Liquid water freezing at a temperature above its freezing point. the melting of ice takes place with the increase or absorbing the heat which is a nonspontaneous,

(c) The combustion of gasoline produces gas molecules, and release energy which means it is an exothermic reaction, the combustion of gasoline is a spontaneous reaction.

(d) A ball is thrown into the air is not a natural process and it requires force or energy to be complete and works against gravity, Therefore, it is a nonspontaneous reaction.

(e) A raindrop falling to the ground is a naturally occurring reaction without any external force and in the direction of gravity, thus it is a spontaneous reaction.

(f) Iron rusting in a moist atmosphere is a spontaneous reaction as it does not require energy to occur and it naturally takes place. It is a redox reaction.

Answer:

The Answer is gonna be Indroduction of non-native plant species

Answer: 2.40 X10^24

Explanation: Utilizing Avogadro's Number of 6.022 X 10^23

112gSi X 1molSi/28.09gSi X 6.022 X 10^23/1molSi = 2.40 X 10^23