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Answer: The formula for magnesium carbonate is MgCO_3.

Explanation:

Answer:

B. Iron (7.8 g/mL)

Explanation:

23.4/3 = 7.8

7.8g/mL

The identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.

The density of a substance can be calculated by dividing the mass of the substance by its volume. That is;

Density = mass (g) ÷ volume (mL)

According to this question, a sample of a metal has a mass of 23.4 g and a volume of 3.0 mL. The density of the metal is as follows:

Density = 23.4g ÷ 3mL

Density = 7.8g/mL

Therefore, the identity of a sample of a metal that has a mass of 23.4 g and a volume of 3.0 mL is iron with a density of 7.8g/mL.

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Answer:

Mass percentage of NH₄Cl = 3.54%

Mass percentage of K₂CO₃ = 1.01%

Explanation:

If a 200.0 mL aliquot produced  0.105 g of KB(C₆H₅)₄, then a 100.0 mL aliquot would produce 1/2 * 0.105 g = 0.0525 g of KB(C₆H₅)₄.

Therefore, mass of NH₄B(C₆H₅)₄ in the 100.0 ml aliquot = (0.277 - 0.0525)g = 0.2245 g

Number of moles of NH₄B(C₆H₅)₄ in 0.2245 g = 0.2245 g/ 337.27 g/mol = 0.0006656 moles

In 500 ml solution, number of moles present = 0.0006656 * 500/100 = 0.003328 moles.

From equation of the reaction; mole ratio of  NH₄⁺ and NH₄B(C₆H₅)₄ = 1:1

Similarly, mole ratio of  NH₄⁺ and NH₄Cl = 1:1

Therefore, moles of NH₄Cl in 500 ml sample = 0.003328 moles

Mass of NH₄Cl  = 0.003328 mol * 53.492 g/mol = 0.178 g

Mass percentage of NH₄Cl = (0.178/5.025) * 100% = 3.54%

Number of moles of KB(C₆H₅)₄ in 0.105 g (precipitated from 200.0 ml aliquot) = 0.105 g/ 358.33 g/mol = 0.000293 moles

In 500 ml solution, number of moles present = 0.000293 * 500/200 = 0.0007326 moles.

From equation of the reaction; mole ratio of  K⁺ and KB(C₆H₅)₄ = 1:1

Similarly, mole ratio of  K⁺ and K₂CO₃ = 2:1

Therefore, moles of K₂CO₃ in 500 ml sample = 0.0007326/2 moles =  0.0003663 moles

Mass of  K₂CO₃ = 0.0003663 mol * 138.21 g/mol = 0.05063 g

Mass percentage of K₂CO₃ = (0.05063/5.025) * 100% = 1.01%

A descriptive model of Earth's layers can be categorized as prototype model. Hence, option B is correct.

What is a descriptive model?

A descriptive model describes a system or other entity and its relationship to its environment.

The Earth has different compositional and mechanical layers. Compositional layers are determined by their components, while mechanical layers are determined by their physical properties.

The outermost solid layer of a rocky planet or natural satellite. Chemically distinct from the underlying mantle.

Hence, option B is correct.

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Answer:4

Explanation:

4

Answer:

Distillation will be the best method for the separation of solute from the solvent in a solution.

Explanation:

Answer:

Lithium would require the least amount of energy to remove an electron

Answer:

The answer is actually sodium

Explanation:

Lithium actually requires more than sodium.

Answer:

The answer is

[tex]3.77 \times {10}^{15} \: \: \: Hz[/tex]

Explanation:

The frequency of the photon can be found by using the formula

[tex]f = \frac{E}{h} \\ [/tex]

where

E is the energy

f is the frequency

h is the Planck's constant which is

6.626 × 10-³⁴ Js

From the question

E = 2.50 × 10^-18 J

So we have

[tex]f = \frac{2.50 \times {10}^{ - 18} }{6.626 \times {10}^{ - 34} } \\ [/tex]

We have the final answer as

[tex]3.77 \times {10}^{15} \: \: \: Hz[/tex]

Hope this helps you

Answer:

This statement is the definition of law of conservation of mass.

Explanation:

Law of conservation of mass:

According to the law of conservation mass, mass can neither be created nor destroyed in a chemical equation.

This law was given by French chemist  Antoine Lavoisier in 1789. According to this law mass of reactant and mass of product must be equal, because masses are not created or destroyed in a chemical reaction.

For example:

In given photosynthesis reaction:

6CO₂ + 6H₂O   →   C₆H₁₂O₆ +  6O₂

there are six carbon atoms, eighteen oxygen atoms and twelve hydrogen atoms on the both side of equation so this reaction followed the law of conservation of mass.

Let us consider the general chemical reaction.

A   +   B    →      C

5g +  5g           10g

Answer:

The atoms in the solid would be vibrating in position.

Explanation:

i took the test

Three grams of the same substance in different phases are stored in three different containers. Each container is barely large enough to hold the substance. Therefore, the correct option is option B.

Atom, the smallest unit of matter that may be separated without releasing electrically charged particles. It is also the tiniest unit of matter with the characteristics of a chemical substance. As a result, the atomic is the fundamental building component of chemistry.

The majority of the molecule is empty space. The rest of the structure is made up of a positive-charged nucleus of neutrons and protons surrounding by a swarm of negative-charged electrons. In comparison to electrons, the lightest charge particles in nature, nuclear nucleus is small yet dense. The atoms in the liquid would be vibrating in position.

Therefore, the correct option is option B.

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the answer is B transfer thru direct contact

Answer:

As a seed plant grows, the roots grow downward due to the force of​  Gravity

Explanation:

A seed is planted upside-down, but the roots still grow in the direction of gravity.

Answer:

Obviously, it's gravity

Explanation:

Answer:

Explanation:

To find the number of moles in a substance given it's number of entities we use the formula

[tex]n = \frac{N}{L} \\ [/tex]

where n is the number of moles

N is the number of entities

L is the Avogadro's constant which is

6.02 × 10²³ entities

From the question we have

[tex]n = \frac{2.16 \times {10}^{26} }{6.02 \times {10}^{23} } \\ = 358.80398671...[/tex]

We have the final answer as

Hope this helps you

Answer:

C. Elements bond in a multitude of ways to make compounds.

Answer:

Ok what question

Explanation:

Answer:

Answer

The answer is option 4

The energy transformation during nutrients transportation across the cell membrane is transformation from chemical energy to kinetic energy, where the uphill and downhill movements of molecules based on concentration gradient carries the whole process.

The total energy in a system is always conserved. However, one form of energy can be transformed into another form. For example we uses electrical devices such as bulbs fan etc, wherever the energy transformation is getting way from electrical energy to light or mechanical energy.

In plant cells nutrient molecules and ions are balanced inside and outside the cell and hence they are transported across the cell membrane by a concentration gradient with a chemical energy produced by the molecules.

The chemical energy inside of the ions and molecules converts to kinetic energy to transport itself through downhill and uphill mechanisms with aid of various enzymes and electron channels.

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Answer:

37 negative charges.

Explanation:

We're being asked to determine how many negative charges a drop contains from an oil drop experiment where the total charge was 5.93x10-18 C. The drop contains 37 negative charges.

It was stated and identified that we are to attempt question #51 alone.

From the given information;

The total charge on an oil drop = 5.93 × 10⁻¹⁸ C

According to Oil drop experiment carried out by Robert Milliken in (1910);

In the oil drop laboratory experiment, It was possible for Him to substitute oil for water (because water quickly evaporate). Robert Milikan adjusted the electrical voltage among the two metal plates while the oil drop continues to drop until it stopped. When the drop was stopped, the gravitational downward force on the oil drop was equivalent to the electrical upward force on the charges thereby enabling Robert Millikan to be able to estimate the electrical charge drop.

Robert Milliken identified that the magnitude of a single negative electron charge is:

= 1.6 × 10⁻¹⁹ C

∴

If in an experiment, the total charge =  5.93 × 10⁻¹⁸ C

Then;

The number of negative charges in the oil drop can be calculated as;

[tex]\mathbf{=\dfrac{5.93 \times 10^{-18}}{1.6 \times 10^{-19}}}[/tex]

= 37.063 negative charges

Therefore, we can conclude that the numbers of negative charges contained in the total drop = 37.063.

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Answer:

2,3,5

Explanation:

Answer:

C I think.

Explanation:

Sorry if it's wrong :(

Answer:

Tobacco use: The most preventable cause of cancer death

Explanation:

cancer might not be right

Answer:

Overfishing

Explanation:

The aquatic biomes of the Philippines' are rich in coral reefs and other aquatic animals but they are under major threat due to pollution and overfishing.

Pollution is caused by industrial factories and coastal developments. Industrial factories fed all it waste in the aquatic biomes and coastal developments due to the increasing population of the Philippines causes mass pollution by the dumping of waste materials and sedimentation.

Overfishing exploits the fish species and also affects the food cycle in aquatic biomes.

As a student, we can spread awareness by conducting awareness campaigns and can take the help of news channels to let people know the consequences of aquatic biomes exploitation. We can also use social media which is popular nowadays to introduce facts about the causes and consequences of aquatic biomes exploitation.

Answer: Water is considered neutral because the concentration of hydrogen and hydroxide ions is the same

Explanation:

Answer:

Explanation:

molecular weight of potassium hydrogen phthalate = 204

.8094 g of KHP = .8094 / 204 = 3.967 x 10⁻³ moles

3.967 x 10⁻³ moles of KHP must have reacted with 3.967 x 10⁻³ moles of NaOH

concentration of NaOH = 3.967 x 10⁻³ / 40.25 x 10⁻³

= .098 M .

Answer: 24.309amu

Explanation:

Answer:

I will not consider electronic mass here. We know (the masses should have been provided in the question!) that the neutron mass is

1.008701

⋅

amu

and the proton mass is

1.007316

⋅

amu

.

Explanation:

Question answered