Give the number of covalent bonds that a carbon atom can form.

Answer:

[tex]\boxed{\text{True; False; True}}[/tex]

Explanation:

Catalysts lower activation energy. TRUE.  

They provide an alternate pathway with a lower activation energy.

Catalysts are consumed by the overall reaction. FALSE.

They take part in the reaction, but they can be recovered unchanged at the end.

Catalysts speed up the chemical reactions. TRUE.

If the activation energy is lowered, a greater percentage of the molecules will have enough energy to get over the energy barrier.

Its like lowering the high-bar in a track and field meet. The lower the bar, the more athletes will be able to get over it.

Cholesterol is an example of a lipid.

Cholesterol is an example of a(n) lipid. Hence, option C is correct.

A lipid is any of various organic compounds that are insoluble in water.

Cholesterol is one of several types of fats (lipids) that play an important role in your body.

Cholesterol is a waxy substance found in all cells of the body.

The body needs it to make hormones, Vitamin D, and substances that aid in digestion.

The liver makes all the cholesterol needed for these functions.

Hence, option C is correct.

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Answer:

40.73 L.

Explanation:

where, P is the pressure of the gas in atm (P = 121.59 kPa/101.325 = 1.2 atm).

V is the volume of the gas in L (V = ??? L).

n is the no. of moles of the gas in mol (n = 2.0 mol).

R  is the general gas constant (R = 0.082 L.atm/mol.K),

T is the temperature of the gas in K (T = 25°C + 273 = 298 K).

∴ V = nRT/P = (2.0 mol)(0.082 L.atm/mol.K)(298 K)/(1.2 atm) = 40.73 L.

Answer:

Explanation:

The Lewis electron diagram is a representation of the atoms that shows the the valence electrons present in the atom.

The Lewis electron diagram uses the chemical symbol of the element and adds one dot for every valence electron. The dots (valence electrons) are placed around the chemical symbol.

So, for phosphorues:

So you get the picture attached, with the chemical symbol P at the center, surroundeb by 5 dots: two dots above, one dot to the left, one dot to the right, and one dot below the chemical symbol.

Please, click on the image if you want to see it separately

The Lewis electron dot diagram for phosphorus shows five dots arranged around the elemental symbol 'P', indicating the five valence electrons.

The student has asked for the Lewis electron dot diagram for phosphorus based on its electron configuration, which is 1s²2s²2p⁶3s²3p³. Phosphorus has a total of 15 electrons with the valence electrons being the most important for the Lewis structure. Considering the electron configuration, phosphorus has 5 valence electrons (in the 3s and 3p subshells). The Lewis dot diagram represents these 5 valence electrons as dots surrounding the symbol for phosphorus (P):

P : . .
  .
  .

The correct answer is B).

Answer:

B) use 0.2 M HCl

Explanation:

Lowering the concentration of a reactant will slow down the rate of reaction. If she would use 0.2 M HCl, the reaction rate will be slower than with 1.0 M HCl. The other choices would increase the rate of reaction, making it even more dangerous.

Answer:

One mole of H₂S contains 2 atoms of hydrogen

Explanation:

In one mole of NaOH : 1 atom of Na and 1 atom of O and 1 atom of H

    one mole of H₂S   :  2 atoms of H and 1 atom of S

     one mole of NH₃  : 1 atom of N and 3 atoms of H

     One mole of CH₄ : 1 atom of C and 4 atoms of H

The work performed by the chemists can be considered as the useful effect to fix a problem, while some work found to harm the environment. Thus, option C is correct.

Chemists are the group of individuals that deal with the drugs and the medicines. The research made the development of the new drugs and the compounds that are used by the population to treat several diseases.

The chemicals dealt by chemist are formed to be sensitive, and can be used to fix the problems, while sometimes the effect creates the compound that harm the environment.

Thus, option C is correct.

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An indicator in a titration indicates when the reaction has reached its equivalence point by undergoing a noticeable color change. This color change marks the end point of the titration, providing an estimate for more accurate calculations of analyte concentration.

The function of an indicator in a titration is to show when a reaction has reached its equivalence point, which is typically determined by a noticeable change in the color of the solution. Indicators like methyl orange, litmus, or phenolphthalein are substances that change color at or near the equivalence point of the titration. These color changes, which are sensitive to the pH level of the solution, mark the end point of the titration, allowing for accurate measurements and calculations of analyte concentration.

For instance, in a strong acid titration, the solution pH hits the lower limit of the methyl orange color change interval after the required amount of titrant has been added, thus changing the initial red solution to appear orange. On reaching the equivalence point, the solution turns yellow, suggesting the endpoint of the titration. Similarly, phenolphthalein goes colorless to pink around the equivalence point, helping to identify when the titration has been completed.

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The function of an indicator in a titration is to signal the end point of the reaction, which ideally corresponds to the equivalence point.

In titration, an indicator is a substance that changes color at a specific pH level, which is chosen to match the completion of the chemical reaction being studied. The equivalence point is the point at which the amount of titrant added is stoichiometrically equivalent to the amount of analyte in the solution. Since the equivalence point cannot be observed directly, an indicator is used to mark the end point, which is a visible change that occurs at or very near the equivalence point.

 The choice of indicator is crucial and depends on the nature of the titration. For acid-base titrations, indicators are selected based on their pKa values, which should be close to the pH at the equivalence point. For example, phenolphthalein is commonly used for strong acid-strong base titrations because it changes color in the pH range of 8.2 to 10.0, which is suitable for such reactions.

 The accuracy of the titration can be affected by the choice of indicator. If the pKa of the indicator is not close enough to the pH of the equivalence point, the end point and equivalence point may not coincide, leading to a titration error. Therefore, a good indicator should have a sharp color change within a narrow pH range that brackets the expected pH at the equivalence point.

In summary, the function of an indicator in titration is to provide a clear, observable change that indicates when the equivalence point has been reached, allowing for the precise determination of the concentration of the analyte.

Answer:

113.8g

Explanation:

Statement of problem: mass of 1.946mole of NaCl

Given parameters:

Number of moles of NaCl = 1.946mole

Unknown: mass of NaCl

Solution

To find the mass of NaCl, we apply the concept of moles which expresses the relationship between number of moles and mass according to the equation below:

                        Number of moles = [tex]\frac{mass}{molar mass}[/tex]

To find the molar mass of NaCl:

                         the atomic mass of Na = 23g

                                atomic mass of Cl = 35.5g

                Molar mass of NaCl = (23 + 35.5) = 58.5gmol⁻¹

Mass of NaCl = Number of moles x molar mass of NaCl

Mass of NaCl = 1.946 x 58.5 = 113.8g

There would be approximately 113.72 grams in 1.946 moles of NaCl. This is calculated by using the molar mass of NaCl (58.44 g/mol) and multiplying it by the number of moles given.

To find out how many grams are in 1.946 moles of NaCl, you need to use the molar mass of NaCl. The molar mass is the mass of one mole of a substance and for NaCl, it is calculated by adding the atomic masses of Sodium (Na) and Chlorine (Cl), which is approximately 58.44 grams per mole. Therefore, to find out the mass in grams of 1.946 moles of NaCl, you multiply 1.946 moles by the molar mass of NaCl, 58.44 g/mol.

1.946 moles NaCl * 58.44 g/mol NaCl = 113.72 grams NaCl

So, 1.946 moles of NaCl is approximately equal to 113.72 grams.

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Because only those with logic (problem solving capabilities) go to chemistry.

Chemists are great for solving problems due to their analytical skills and systematic approach to research.

They have a deep understanding of chemical properties and reactions, which allows them to develop solutions to complex issues. Their training in laboratory techniques equips them to design and conduct experiments effectively.

Chemists can identify and isolate variables, making it easier to pinpoint the root cause of a problem. They also excel in data analysis, interpreting results to draw meaningful conclusions.

Their ability to think critically and creatively helps them devise innovative solutions. Furthermore, chemists are skilled in collaborating with other scientists and professionals, bringing a multidisciplinary approach to problem-solving.

This combination of skills and knowledge makes chemists highly effective in addressing and resolving a wide range of challenges.

The answer is D

Hope this helped

Answer:

If you only want to look at concerns then B would be the correct answer because that is a positive when using nuclear energy

Explanation:

Answer:

4 atoms.

Explanation:

1 atom of C and 4 atoms F.

So, a molecule of carbon tetrafluoride contains 4 atoms of flourine.

Answer: It contracts  and its density decreases, I believe.

Explanation:

Answer:

its density decreases

Explanation:

The concept illustrated in the question, "Do you own a dog?", is a control question. A control question is used to establish a baseline response for comparison.

The concept illustrated in the question, "Do you own a dog?", is a control question.

A control question is a type of question used to establish a baseline response for comparison. It is typically unrelated to the topic being discussed and is used to ensure the accuracy and reliability of the answers given.

In this example, asking someone if they own a dog would serve as a control question if the actual topic of conversation is something unrelated to dogs or pets.

Hi there,

Your answer is given in the image attached above

Answer:

Option B. 20 oC

Explanation:

Thinking process:

The initial reaction takes place at: 0.01840 M/s at 25 oC.

However, the rate must be reduced to 0.0046 M/s.

It is most likely that a temperature of 20 °C is used her. This is because it offers sufficient kinetic energy to effect the reaction rate of the reaction substances.

Cations, or positive ions, are smaller than their parent atoms because they have fewer electrons resulting in less electron-electron repulsion. Anions, or negative ions, are larger than their parent atoms because additional electrons increase electron-electron repulsion.

The true statement in the choices given is: 'Cations are smaller than their neutral parent atoms because there are fewer electrons "competing" for the attractive force of the protons in the nucleus'.

When an atom forms a cation, or a positive ion, it loses one or more electrons from its valence shell. This reduction in the number of electrons minimizes the electron-electron repulsion and allows the protons in the nucleus to pull the remaining electrons closer, making the radius of the cation smaller than the parent atom. For example, an aluminium atom has a larger radius than an aluminium cation because the cation has fewer electrons, hence the remaining electrons are pulled closer to the nucleus.

On the other hand, anions form when a neutral atom gains one or more electrons in its valence shell. The added electrons increase repulsion among the electrons, causing the radius of an anion to be larger than that of its parent atom. For example, a sulfur atom has a smaller radius than a sulfide anion because the anion has more electrons, thus they spread out more due to increased electron-electron repulsion.

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The correct statement is that cations are smaller than their neutral parent atoms because there are less electrons competing for the attractive force of the protons in the nucleus. Conversely, anions are larger than their neutral parent atoms due to more electrons competing for the attractive force of the protons.

The correct statement is: Cations are smaller than their neutral parent atoms because there are fewer electrons “competing” for the attractive force of the protons in the nucleus. A cation is a positively charged ion that is formed when a neutral atom loses one or more electrons from its valence shell. This loss of electrons results in a smaller atomic radius because there are fewer electrons 'competing' for the attractive force of the protons, allowing the atom to pull the remaining electrons closer to the nucleus.

Conversely, an anion is a negative ion that is formed when a neutral atom gains one or more electrons. This results in a greater repulsion among the electrons, which results in an increase in atomic radius. Hence, anions are larger than their neutral parent atoms because there are more electrons “competing” for the attractive force of the protons in the nucleus.

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Answer: since it has a very reactive sulfhydryl group at its side chain. This puts cysteine in special position that cannot be replaced or substituted by any other amino acid. Because disulfide bridges formed by cysteine residues are permanent component of protein primary structure.

Explanation:

Answer:

12.5 atm.

Explanation:

Ptotal = P1 + P2 + … + Pn.

∴ Ptotal = P of gas 1 + P of gas 2 + P of gas 3 + P of gas 4 + P of gas 5.

∴ Ptotal = 5(2.5 atm) = 12.5 atm.

Answer:

Explanation:

1) Word reaction:

This is a single replacement reaction, in which aluminum, a more acitve metal than iron, replaces the iron in the ferrous oxide to form aluminum oxide and iron.

2) Skeleton chemical equation:

3) Balanced chemical equation:

Add the coeffcients to comply with the law of conservation of mass:

4) Mole ratio of Al and FeO:

5) Set a proportion with the unkown and solve:

Answer:

D. The process in which a substance gains energy

Explanation:

An endothermic reaction is a reaction in which heat energy is absorbed from the surroundings therefore we can imply that in such reaction, the substances gains energy. In endothermic reactions, the surrounding becomes colder at the end of the changes.

Here, the heat energy level of the final state is higher than that of the initial state. Most dissolution reactions are endothermic in nature. Examples are dissolution of Sodium chloride in water.

Note: it is in exothermic reaction that heat energy is liberated to the surrounding

Answer:

D. The process in which a substance gains energy

Explanation:

3.44x10^23 divided by 6.02x10^23 equals 0.571 mol Cu.

Final answer:

To find the number of moles equivalent to 3.44 × 10²³ atoms of copper, you divide the given number of atoms by Avogadro's number, resulting in approximately 0.571 moles of copper.

Explanation:

To calculate the number of moles of copper equivalent to 3.44 × 10²³ atoms of copper, we need to use Avogadro's number, which is approximately 6.02 × 10²³ atoms/mol. This is the number of atoms in one mole of any element.

Here is the step-by-step calculation:

Therefore, there are roughly 0.571 moles of copper in 3.44 × 10²³ copper atoms.

Answer:

See below  

Explanation:

[tex]\rm HCOOH + H_{2}O \rightleftharpoons H_{3}O^{+} + HCOO^{-}[/tex]

The general formula for an equilibrium constant expression is

[tex]K_{eq} = \dfrac{[\text{Products}]}{[\text{Reactants}]}[/tex]

For this reaction,  

[tex]K_{eq} = \dfrac{[\text{HCOO}^{-}][\text{H}_{3}\text{O}^{+}]}{[\text{HCOOH}]}[/tex]

The true statement for a solution when its concentration of hydronium ions increases then pH decreases.

pH of any solution is used to define the acidity, basicity or neutrality of the solution.

pH will be calculated as:

pH = -log[H⁺]

From the equation it is clear that concentration of hydronium ion increases, pH value decreases and acidity increases.

Hence, pH value decreases as hydronium ion increases.

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Answer:

[tex]\boxed{\text{1.81 da}}[/tex]

Explanation:

1. Calculate the decay constant

The integrated rate law for radioactive decay is 1

[tex]\ln\dfrac{A_{0}}{A_{t}} = kt[/tex]

where

A₀ and A_t are the counts at t = 0 and t

k is the radioactive decay constant

[tex]\ln \dfrac{846}{269} = k \times 3.00\\\\\ln3.145 = 3.00k\\1.146 = 3.00k\\\\k =\dfrac{1.146}{3}\\\\k = \text{0.382 /da}\\[/tex]

2. Calculate the half-life

[tex]t_{\frac{1}{2}} = \dfrac{\ln2}{k} = \dfrac{\ln2}{0.382} = \text{1.81 da}[/tex]

The half-life for decay is [tex]\boxed{\textbf{1.81 da}}[/tex].

Answer:

C. the last one

Explanation:

Cysteine's unique characteristic is its ability to form disulfide bridges, covalent bonds that provide structural stability to proteins. The formation of these bridges is a unique property of cysteine among the amino acids, even though it, like others, can form hydrogen bonds.

The unique characteristic of the amino acid cysteine is its ability to form disulfide bridges. These bridges are covalent bonds that provide structural stability to proteins. While cysteine is capable of forming hydrogen bonds like other amino acids, its special characteristic is indeed the formation of these disulfide bridges. Two cysteine residues can come together to form a disulfide bridge, helping to stabilize the three-dimensional structure of the protein. It is notable that hydrogen bonds are weak interactions that occur broadly between many different molecules, but the covalent bonding of disulfide bridges is a unique property of cysteine within the amino acid series.

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C) Space exploration gives scientists important data they can use to determine the origin of the universe.

Answer:

C) Space exploration gives scientists important data they can use to determine the origin of the universe

Explanation:

Space is being explored from decades now in order to accumulate data that can provide us knowledge about origin of universe and, moreover it may help us finding some different natural resources which are not present on earth. Voyager 1 and 2 are such huge milestone in providing data that is being used for our concerns.

Answer:

All of the above

Explanation:

Panthers, pumas, and mountain lions are all the same animal. Just different names. So, all of these would be correct.

Answer:

Kindly find the attached image.

Explanation:

Reactants, intermediate, products, activation energy (Ea), and enthalpy change (ΔH).

ΔH = E of products - E of reactants.

Answer: Arrow E represents the enthalpy of the reaction.

Explanation:

Enthalpy of the reaction is defined as the difference in the potential energy of the products and the reactants. It is represented as [tex]\Delta H_{rxn}[/tex]

[tex]\Delta H_{rxn}=H_{products}-H_{reactants}[/tex]

From the image, the points marked represents:

Point A represents the potential energy of the reactants.

Point B represents the intermediate state or transition state in a reaction.

Point C represents the potential energy of the products.

Arrow D represents the activation energy of the reaction.

Arrow E represents the enthalpy of the reaction.

Hence, arrow E represents the enthalpy of the reaction.

Answer:

its d 3.9 not c

Explanation:

To find the maximum amount of magnesium oxide produced during the reaction, we need to determine the limiting reactant and calculate the moles of magnesium oxide produced. Using the mole ratio and converting grams to moles, we find that the maximum amount is 3.99 grams.

To determine the maximum amount of magnesium oxide that can be produced during the reaction, we need to find the limiting reactant. First, we convert the given masses of magnesium and oxygen to moles using their respective molar masses. The balanced chemical equation tells us that the mole ratio of magnesium to magnesium oxide is 1:1, so the number of moles of magnesium is equal to the number of moles of magnesium oxide. Lastly, we convert the moles of magnesium oxide to grams using its molar mass to find the maximum amount of magnesium oxide that can be produced.

Therefore, the maximum amount of magnesium oxide that can be produced during the reaction is 3.99 grams.

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Answer:I believe your answer would be option B) dilute. Hope this helps.

Explanation:

The correct answer is B) Dilute

Explanation:

In a solution, the proportions of the solute vs the solvent determine the type of solution that includes dilute/concentrated or unsaturated, saturated and supersaturated. In the case of a dilute solution, this occurs if there is a small amount of the solute in comparison to the amount of solvent, which makes it possible to add more solute as this can be dissolved. This type of solution applies to the case presented because one gram of salt (solute or substance dissolved) is a small quantity of solute in comparison to the amount of solvent (the substance that dissolves) that in this case is 100 liters of water. Thus, in this case, there is a dilute solution.