Complete the following math problem and round your answer to the correct number of significant figures. Explain why your answer has that number of decimal places or significant figures.

12.65 + 11.2

Answer:

The correct row is B.

Explanation:

The formation of the magnesium ion, Mg²⁺, comes from the removal of 2 electrons from the valence shell of the magnesium atom. Since the remotion is of electrons, the nucleus of the atom remains the same, so the number of protons and the number of neutrons does not change.

If the number of proton change, then the atom also change, since the identity of an atom is related to the atomic number which is the same to the proton number.          

Now, if the number of neutrons changes, then we would be in the presence of an isotope of the magnesium atom.        

Therefore, the correct row is B.  

I hope it helps you!                            

The molarity of the KMnO4 solution is 0.532 M (rounded to three decimal places).

To calculate the molarity of the KMnO4 solution, we need to use the stoichiometry of the reaction and the volume of the KMnO4 solution used in the titration.

Given:

Mass of H2O2 solution = 1.0 g

Concentration of H2O2 solution = 30 wt% (weight percent)

Volume of KMnO4 solution used = 22.143 mL

Molar mass of H2O2 = 34.01 g/mol

Step 1: Calculate the moles of H2O2 in the solution.

Moles of H2O2 = (Mass of H2O2 solution) / (Molar mass of H2O2)

= 1.0 g / 34.01 g/mol

= 0.0294 mol

Step 2: Calculate the moles of KMnO4 based on the stoichiometry of the reaction.

According to the balanced equation, the ratio of KMnO4 to H2O2 is 2:5.

Therefore, moles of KMnO4 = (Moles of H2O2) * (2/5)

= 0.0294 mol * (2/5)

= 0.01176 mol

Step 3: Calculate the molarity of the KMnO4 solution.

Molarity (M) = (Moles of KMnO4) / (Volume of KMnO4 solution in liters)

= 0.01176 mol / 0.022143 L

= 0.5316 M

Therefore, the molarity of the KMnO4 solution is 0.532 M (rounded to three decimal places).

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Launching a projectile over a significant distance, such as several hundred miles, presents a range of complex challenges that must be carefully addressed. The success of achieving such a long range relies on accounting for various factors that influence the projectile's trajectory, including aerodynamics, atmospheric conditions, Earth's curvature, and external forces.

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Answer:

Mass extinctions happen because of climate change, asteroid impacts, massive volcanic eruptions or a combination of these causes.

Explanation:

Answer:

Explanation:

A natural disaster is a major adverse event resulting from natural processes of the Earth; examples include floods, hurricanes, tornadoes, volcanic eruptions, earthquakes, tsunamis, storms, and other geologic processes

Answer:

A natural disaster is a natural, major harmful event resulting from natural processes of the Earth such as floods, earthquakes, or hurricanes, tornadoes, volcanic eruptions, tsunamis, storms, and other geologic processes that causes great damage or loss of life.

If 170 milligrams of a radioactive substance decays to 85 g after 16 hours. Then, after 21 hours, approximately 75.2 mg of the radioactive substance will remain.

The decay of the radioactive substance follows an exponential decay equation of the form:

\(N(t) = N_{o} \times e^{-kt}\)

Where:

N(t) is the amount of substance remaining at time t

N₀ is the initial amount of substance

k is the decay constant

t is the time elapsed

Given to us is N₀ = 170 mg and N(16) = 85 mg. We can use this information to find the decay constant, k.

\(85 = 170 \times e^{-k \times 16}\)

Dividing both sides by 170:

\(0.5 = e^{-k \times 16}\)

To solve for k, we can take the natural logarithm (ln) of both sides:

ln(0.5) = -k × 16

from this, the value of k comes out to be:

k = 0.0431

Now we can use the decay equation to find the amount of substance remaining after 21 hours, N(21):

\(N(21) = 170 \times e^{-0.0431 \times 21}\)

Calculating this expression:

N(21) = 75.2

Therefore, after 21 hours, approximately 75.2 mg of the radioactive substance will remain.

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None of these, as Mg/ether and CH3Br are not the correct reagents for this specific conversion. The reagents necessary to carry out the conversion of CH3Li to CH3MgBr to (CH3)2CuLi would be:

1. CH3Li + MgBr2 → CH3MgBr (Grignard reagent)
2. CH3MgBr + CuI → (CH3)2CuLi

Therefore, the correct answer would be none of these, as Mg/ether and CH3Br are not the correct reagents for this specific conversion.
1. Start with CH3Li (methyl lithium) as the base compound.
2. Perform a transmetallation reaction by reacting CH3Li with Mg/ether (magnesium in ether) to produce CH3MgBr (methyl magnesium bromide).
3. Next, use (CH3)2CuLi (dimethyl copper lithium) to react with CH3MgBr, forming a Gilman reagent.

So, the reagents necessary for the conversion are Mg/ether and (CH3)2CuLi. Please note that CH3Br and "none of these" are not part of the answer since they are not required for the conversion process.

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Fatty acids are part of the structure of many lipids except for sterols.

What are lipids?

Lipids are macromolecules made up of hydrocarbon chains or rings, which means that they contain a lot of energy. Lipids are organic molecules that contain carbon, hydrogen, and oxygen in a proportion that varies depending on the specific molecule. They are non-polar and insoluble in water, which means that they do not dissolve in water.

Lipids are categorized into three different classes: Fats and oils (triglycerides), phospholipids, and steroids. They are essential to many cellular functions, including energy storage, insulation, and membrane formation.

Examples of lipids include butter, oil, and cholesterol.

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Answer:

N20

Explanation:

Answer:

Decomposition reaction

Explanation:

A single reactant breaking down to form 2 or more products is decomposition

The reaction that follows the law of conservation of mass is \(\rm 2\;H_2\;+\;O_2\;\rightarrow\;2\;H_2O\). Thus, option C is correct.

The law of conservation of mass has been stating that in a chemical reaction, the mass at the product and reactants has been equal.

The atoms has been conserved in the reaction that follows the law of conservation of mass.

The moles of reactants and products in the following reactions has been:

A. \(\rm H_2\;+\;O_2\;\rightarrow\;H_2O\)

Hydrogen: The atoms in reactant=2

Atoms in product=2

Oxygen: The atoms in reactant=2

Atoms in product=1

The product and reactant are not equivalent, thus it not follows the law of conservation of mass.

B. \(\rm H_2\;+\;O_2\;\rightarrow\;H_2O\;+\;4\;He\)

Hydrogen: The atoms in reactant=2

Atoms in product=2

Oxygen: The atoms in reactant=2

Atoms in product=1

He: The atoms in reactant=0

Atoms in product=4

The product and reactant are not equivalent, thus it not follows the law of conservation of mass.

C. \(\rm 2\;H_2\;+\;O_2\;\rightarrow\;2\;H_2O\)

Hydrogen: The atoms in reactant=4

Atoms in product=4

Oxygen: The atoms in reactant=2

Atoms in product=2

The product and reactant are equivalent, thus it follows the law of conservation of mass.

D. \(\rm \;H_2\;+\;O_2\;\rightarrow\;2\;H_2O\)

Hydrogen: The atoms in reactant=2

Atoms in product=4

Oxygen: The atoms in reactant=2

Atoms in product=2

The product and reactant are not equivalent, thus it not follows the law of conservation of mass.

The reaction that follows the law of conservation of mass is \(\rm 2\;H_2\;+\;O_2\;\rightarrow\;2\;H_2O\). Thus, option C is correct.

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The picture of atoms in a compound known as a Lewis dot structure demonstrates an atom's stability.

A few potential names for element E are:

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Complete question is

Consider the following Lewis structure, where E is an unknown element.

What are some possible identities for element E? Predict the molecular structure (including bond angles) for this ion.

When a positively charged rod is brought near a charged electroscope, the electroscope leaves move closer to each other, indicating that the electroscope has a negative charge.

When a positively charged rod is brought near a charged electroscope, the positively charged rod polarizes the charges in the electroscope. Initially, the electroscope may have a neutral charge, meaning the number of positive and negative charges within it are balanced. However, when the positively charged rod is brought close to the electroscope, it repels the positive charges in the electroscope and attracts the negative charges.

As a result, the positive charges within the electroscope are pushed away from the rod, while the negative charges are attracted toward it. This redistribution of charges creates a separation of charge within the electroscope.

Since the positive charges are repelled and move away from the leaves of the electroscope, the negatively charged leaves experience a net attractive force. This force pulls the leaves closer together, causing them to move toward each other.

Therefore, the electroscope acquires a negative charge as a result of the positively charged rod being brought near it.

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Answer:

353 ppm

Explanation:

PPM also refers to parts per million, it represents a low concentration of a solution. It represents 0.001 gram or a milligram in 1000 mL, equivalent to 1 mg per liter

Given that;

276 mg of Ca in 780.0 g of water

1 ppm = 1 mg/L

780 g = 780 mL = 0.78 L

Therefore;

= 276 mg/ 0.78 L  

=  353.84mg/L

= 353 ppm

Answer:

A

Explanation:

Igneous rock forms from cooled lava

If the bromobenzene is added too quickly, biphenyl is formed as the side product with the Grignard reagent.

What is Grignard reagent?

Grignard reagent is an organomagnesium halide which has the formula RMgX where R is alkyl or aryl group, Mg is magnesium, X is an halide.

When bromobenzene is added too quickly to the Grignard reagent, biphenyl is formed as a by-product. the formation of the side product is enhanced by high temperature. So, this reaction is carried out in low temperature.

Therefore, biphenyl is formed as side product when bromobenzene is added quickly to the Grignard reagent. The structure of biphenyl is two benzene rings joined together.

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We must start with 368.82 grams of Al to produce 6.83 mol of \(Al_{2} O_{3}\) .

The balanced reaction for the equation as follows:

\(4Al + 3O_{2}\) ⇒ \(2Al_{2} O_{3}\)

As we can see that 4 moles of Al reacts with 3 moles of \(O_{2}\) to produce 2 moles of \(Al_{2} O_{3}\), which means 108 grams of Al reacts with 96grams of \(O_{2}\) to produce 204 grams of \(Al_{2} O_{3}\).

Now,

2 mol of \(Al_{2} O_{3}\) react with 108 grams of Al

So,

6.83 mol of \(Al_{2} O_{3}\) react with = \(\frac{108}{2} *6.83\) grams of Al

6.83 mol of \(Al_{2} O_{3}\) react with = 368.82 grams of Al

Therefore, we must start with 368.82 grams of Al to produce 6.83 mol of \(Al_{2} O_{3}\) .

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Considering the definition of volume, the volume of the box is 30 mL or 0.03 L.

Volume is a metric magnitude that is defined as the extension in three dimensions of a region of space. In other words, it is defined as the amount of space occupied by the object or figure in three-dimensional space. Volume is measured in cubic units.

Volume can be considered as the capacity of a container to hold a quantity of fluid (gas or liquid).

A box is a rectangular prism, which is defined as a prism with rectangular bases and rectangular lateral faces.

The volume of this prism depends on its three dimensions and is calculated as the multiplication of these dimensions:

Volume= Dimension 1× Dimension 2× Dimension 3

In this case, you know that a box has dimensions of 2.5 cm by 3.0 cm by 4.0 cm. So, the volume can be calculated as:

Volume= 2.5 cm× 3 cm× 4 cm

Solving:

Volume= 30 cm³

Being 1 cm³=  1 mL and 1 L= 1,000 mL then:

Volume= 30 cm³= 30 mL= 0.03 L

Finally, the volume of the box is 30 mL or 0.03 L.

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Answer:  4 g/ml

Explanation:

Volume = (90ml-75ml) = 15 ml

Mass = 60g

Density is mass per unit volume = g/ml, in this case

Density = 60g/15ml = 4 g/ml

At room temperature, the speeds of the particles in a mixture of helium and nitrogen in a closed container will vary based on the mass of the individual particles.

Helium atoms are lighter than nitrogen molecules, so they will move at a faster speed on average due to the same temperature being supplied to both gases. This means that helium particles will collide with the walls of the container more frequently and exert more pressure than nitrogen particles. The kinetic theory of gases explains that the average kinetic energy of gas particles is directly proportional to their temperature, but inversely proportional to their mass. Therefore, helium particles will move faster than nitrogen particles at the same temperature. In a mixture of helium and nitrogen gas at room temperature, the particles' speeds differ due to their distinct molecular masses. Helium, being lighter with a molecular mass of 4 g/mol, will have a higher average speed than nitrogen, which has a molecular mass of 28 g/mol.

This occurs because both gases share the same temperature, so their kinetic energies are similar. However, the relationship between kinetic energy, mass, and velocity dictates that lighter particles will travel faster to maintain the same energy level. Therefore, helium particles will generally move more quickly than nitrogen particles in the mixture.

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The energy required to separate the two ions to an infinite distance apart is -1.64 * 10⁻¹⁸ J.

The potential energy required to separate two ions to an infinite distance apart is called lattice energy. The equation for lattice energy is given as follows:

U = -N (A * Z⁺ * Z⁻ / r)

where,U represents lattice energy

N represents Avogadro's constant

A represents the Madelung constant

Z+ represents cation's charge

Z- represents anion's charger represents the distance between the ion centers

As given in the question, the distance between the potassium and chloride ions in potassium chloride is 2.8e⁻¹⁰m.

Thus, putting all the values in the formula of lattice energy, we get;

U = -6.022 * 10²³* (2.31 * 10⁻¹⁰ * 1 * 1 / 2.8 * 10⁻¹⁰)U = -1.64 * 10⁻¹⁸J

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Answer:

5.232

Explanation:

Answer:

c Two hydrogen one oxygen

Explanation:

H2O

Moles of Water

Moles = mass ÷ molar mass

          = 56.00 g ÷ 18.015 g/mol

          = 3.1085 mol

Molecules of Water

Number of molecules = moles × Avogadro's Number

                                    =  3.1085 mol × (6.022 × 10²³ molecules/mol)

                                    =  1.872 × 10²⁴ molecules

Note: We could do all this calculation in one step but I separated it to make it clearer.