Perform the following operations and express the answers in scientific notation SHOW YOUR WORK (Part 2):
1) (3.67*10^2)-(1.6*10^1)

2) (8.41*10^-5) - (7.9*10^-6)

3) (1.33*10^5)-(4.9*10^4)

The pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.

The above situation is a case of buffer solution.

The pH of a buffer solution can be calculated by the Henderson-Hasselbalch equation,

The equation is as follows:

pH = pKa + log[Salt]/[Acid]

In the above case, sodium acetate(CH3COONa) is the salt and acetic acid(CH3COOH) is the acid.

Putting [Salt] = 0.50 M and [Acid] = 0.25 M and pKa = 4.76 in the equation

pH = 4.76 + log[0.50]/[0.25]

pH = 4.76 + log2

pH = 4.76 + 0.30

pH = 5.06

Thus, the pH of a solution prepared by dissolving 2.05 g of sodium acetate in 50 mL of 0.25 M acetic acid is 5.06.

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Answer:

where is flow diagram.....

.........

Answer: Required personnel protection equipment (PPE) must be worn at all times

Explanation:

The pH of an aqueous solution with a hydrogen ion is 8.11

pH is the quantitative measure of the acidity or basicity of aqueous or other liquid solutions

Here given data is concentration of [H⁺]=7.6×10⁻⁹ M

We have to find pH=?

Then,  pH = -log(conc)

Then pH = -log(7.6×10⁻⁹)

pH = 8.11

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The percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.

Let S be the solid sandy mass which is inside the blend

Let G be the gold mass in such a blend

We have to find the percent G by mass

Mixture density can be calculated as

= total blend mass / total blend volume

= 3.10 g/mL

Mixture sum is

S + G = 1 Kg. = 1000g

Complete mixing volume = sand volume + gold volume

Complete mixing volume can be calculated as

=[tex](\frac{sand mass}{sand density} ) + (\frac{gold mass }{gold density} )[/tex]

Total mixture volume:-

[tex]= (\frac{S}{2.84} ) + (\frac{G}{19.3} )\\\\= \frac{(19.3 S + 2.84 G)}{54.812 mL} \\\\Mixture Density = \frac{mass mixture}{mixture volume}\\ \\= 3.10 \frac{g}{mL}[/tex]

⇒ [tex]3.10 = \frac{1000 g}{ \frac{(19.3 S + 2.84 G)}{54.812 mL}}[/tex]

[tex]19.3 S + 2.84 G = 17681\\\\When S+ G = 1000 g\\\\Solving equation:[/tex]

⇒[tex]19.3 S + 2.84 G = 17681[/tex]

∴ [tex]S + G = 1000 g[/tex]

⇒ 19.3 S + 2.84 = 17681

⇒ -2.84 S - 2.84 = -2840

________________________

⇒ 16.46 S = 14841

⇒ S = 901.7g Sand

Given,

⇒ S + G = 1000

⇒ G = 1000 - 901.7 g

⇒ G = 98.3 g Gold

Percentage of gold in the solution is

(98.3/1000) × 100 = 9.83%

Thus, we concluded that the percentage of gold in the sample if a 1.00 kg sample of sand containing some gold has a density of 3.10 g/mL is 9.83%.

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What makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons (option C).

Hydrogen and Helium are two elements in the periodic table. They are the lightest elements in the periodic table.

Also, they both exist as gases at room temperature and are the two most common elements in the universe.

However, hydrogen and helium are removed from other groups of the periodic table. Thisis because hydrogen and helium atoms only have two electrons and the outermost energy level is the first energy level, hence, there can only be two valence electrons.

Therefore, what makes hydrogen and helium so unique and removed from the other groups on the periodic table is that unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.

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The point that would map onto itself after a reflection across the line y = –x is (4, –4). The correct option is d.

A point would have to be on the line in the first place for it to map onto itself following a reflection over the line.

To calculate the point on the given line, just substitute the x-values of the given points and solve for y.

There are three different x-values:  -4, 0, and 4

Substituting these into  y = -x

x = -4  ⇒  y = -(-4) = 4  →  (-4, 4)

x = 0  ⇒  y = -(0) = 0  →  (0, 0)

x = 4  ⇒  y = -(4) = -4  →  (4, -4)

Therefore, the correct option is d, (4, –4).

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The question is incomplete. Your most probably complete question is given below:

(–4, –4) (–4, 0) (0, –4) (4, –4)

Answer:

scientific is a study of things and scientific law is law

Explanation:

you can study scientific a ND and law

hshdfhdh

Answer:

Scientific theories and laws are both factual. However, scientific theories are statements that have been proven over and over again by dozens of scientists. For example, a theory would be that the solar system is heliocentric (planets revolve around the sun). Theories are also subject to change in the event of new technological innovations. Scientific laws are statements that are universal and are based on logic/math. These will not change because they describe what happens and they are rules. For example, Newton's laws of motion would be laws because they are rules of motion. Overall, scientific theories and laws describe why and what happens based on certain conditions and circumstances.

There are 4 * 10^24 atoms of hydrogen  in 0.48 moles of prevacid.

The drug prevacid is used as an antacid. What is does is to reduce the amount of acid that could be produced in the stomach of a person. As a result of this, the drug prevacid is able to relieve a person of heartburn and stomach ulcer.

Thus time, we want to obtain the number of hydrogen atoms that id present in one 0.48  moles of the drug prevacid.

We have that there are 14 hydrogen atoms in prevacid. Thus;

14 * 0.48 * 6.02 * 10^23 = 4 * 10^24 atoms of hydrogen.

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Answer:

If 160.0 g of radioactive iron (59Fe ) is received in the lab today, Then the percentage of the original left after 180 days is 6.25 %.

Radioactive elements are those elements which are made up of those atoms whose nuclei is unstable and emits radiations or undergoes radioactive decay to attain stability or to form stable nuclei.

Given -

t = 180 days

t1/2 = 45 days

So,

n =    t     = 180 = 4

      t1/2       45

Amount of the remaining radioactive iron,

R = R°

     2n

where, n = 4

R =  1   = 0.0625

R°    2₄

To calculate percentage of original sample -

percentage of original sample of iron = R   x 100

                                                                   R°

                                                               = 0.0625 x 100

                                                               = 6.25 %

After 180 days, or 4 half lives, the percentage of radioactive iron remaining is 6.25%.

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Answer: If the amount of fertilizer applied to plants is increased, then plant growth (height) will increase. As the amount of fertilizer increases the plant growth increases.

Explanation: It's correct

The correct answer to the given question is b) The average atomic mass of all isotopes is what an element’s atomic mass is based on in the periodic table.

An element has many isotopic masses, in which elements have same number of protons but different number of neutrons. An element in the periodic table has the average of all the isotopes. Atomic mass is the sum of protons and neutrons, without the involvement of electrons. For example, Chlorine has 2 isotopes Chlorine-35 having atomic mass 35 and Chlorine- 37 having atomic mass 37. The element Chlorine which is found in the periodic table has atomic mass 35.5 u, based on the average atomic masses and their relative abundance.

Therefore, atomic mass of an element on the periodic table is the average of their atomic mass of all isotopes.

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The fungicide reaches to the leaves through the xylem's transpiration pull.

1. The fungicides are the chemicals which are used to removes fungus which on the plants and also stops the growth of fungus present on plants.

2. The fungicides are dissolved in water to make the dilute solution so that when it sprayed on the leaves, it easily absorbed by the soil.

3. The plants have special mechanism which helps in absorption of all the minerals that are present in the soil.

4. The xylem absorb mineral and water in the soil and phloem absorbs nutrients from the soil. Xylem pull ups the solution against the gravity and moves this solution to the surface of the leaves is called transpiration pull.

5. There are 3 mechanism that involved in the movement of fungicide are• Root pressure • Cohesive force • Capillary action

6. All these forces are worked to pull up the solution upward to the leaves.

Thus the xylem is a specialized mechanism present in the plants to pull up the solution upward against the gravity.

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Answer:

0.024 g/mL

Explanation:

The denisty of a substance is a ratio comparing its mass per every 1 unit of volume. Therefore, if you have been given a mass in grams and a volume in milliliters, the unit for denisty (in this case) is g/mL.

Density = ? grams / ? mL

Density = 12 g / 500 mL

Density = 0.024 g/ 1 mL = 0.024 g/mL

The Erosion caused by wind and beating an egg both the changes are physical change.

Erosion is defined as a geographical process in which earthen material will blow away and caused by a natural force such as wind or water.

There are mainly four types of erosion

Physical change can be defined as a type of change where only the physical properties of the matter changes.

Thus, the Erosion caused by wind and beating an egg both the changes are physical change.

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Answer:

Explanation:

ye

Answer:

To measure the volume of a large rock, fill a glass measuring cup up to one half with water. Put your large rock in and measure the new water level. Subtract the original half cup volume of water and the difference is the volume or space that your rock takes up.

Answer:

if the rock is small use a measuring cylinder

Explanation:

Answer:

Assume you have 1g of your sample.

Then 13.6% of this sample is Na, that is 0.136g.

Since you are to find the empirical formula, you need to find the number of moles of Na in 0.136g. You can do that by dividing by the atomic mass of Na: n(Na)=0.136g / 23.0 g/mol = 0.00591 mol

Next, you repeat this for all the other elements.

The last step is to pick the smallest number of moles that you get and divide the others by it. That way you should arrive at whole number coefficients for the empirical formula. The element with the smallest number of moles gets 1 as its coefficient).

If during a spectroscopy experiment a student notes a wavelength peak measurement at 280 nm, then the region of the electromagnetic spectrum observed is the UV region.

The electromagnetic spectrum refers to all types of wavelengths that radiation can emit as light, which involves both visible light and also ultraviolet (UV) radiation.

In conclusion, if during a spectroscopy experiment a student notes a wavelength peak measurement at 280 nm, the region of the electromagnetic spectrum observed is the UV region.

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Taking into account the definition of photon and energy of a photon, the energy per photon is 8.3538×10⁻³⁸ J.

Electromagnetic radiation carries energy, which can be absorbed or emitted. To explain the processes of emission and absortion, Plank and Einstein proposed that the energy of radiation is composed of indivisible units (quanta). In each elemental process only a quantum of light can be emitted or absorbed. Each of these quanta was called a "photon".

The exchanges of energy between matter and radiation take place not continuously, but by discrete and indivisible quantities or quanta of energy. The quantum of energy is proportional to the frequency of radiation.

The relationship between the amount of energy (E) transported by the photon and its frequency (f) is determined by the following expression:

E=h×f

where:

In this case, you know:

Replacing in the definition of energy of a photon:

E= 1.26×10⁶ Hz× 6.63×10⁻³⁴ Js

E= 8.3538×10⁻³⁸ J

Finally, the energy per photon is 8.3538×10⁻³⁸ J.

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Answer:

196.96657 g/m

Explanation:

The molar mass of gold = 196.96657 g/m. The molar mass of gold is defined as the mass of 1 mole of gold atoms - typically specified in grams. Therefore the molar mass of gold is stated in units of grams/mole or g/m. It is also frequently called the Molecular Weight of Gold.

The energy of the photon is 1.5 * 10^-19 J

According to the Bohr model of the atom, the atom is arranged in energy levels. It is possible for an electron to transition from a lower to a higher energy level by the gain of energy. The energy that is gained must be equal to the difference in energy between the lower and the higher energy levels of the atom.

No we know that we could use the Rydberg formula to obtain the wavelength of the photon that is emitted when an electron moves from a higher to a lower energy level with the emission of the energy that was taken in.

Thus;

1/λ = RH (1/n^2 final – 1/n^2 initial)

RH =  1.09678 x 10⁷ m⁻¹

n final = 3

n initial = 5

1/λ =1.09678 x 10⁷ (1/3^2 – 1/5^2)

1/λ = 1.09678 x 10⁷ (0.11 – 0.04)

λ = 1302 nm

E = hc/ λ

E = 6.6 * 10^-34 *  3 * 10^8/1302 * 10^-9

E = 1.5 * 10^-19 J

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In a series circuit, the current can flow through only one path from start to finish.

The term circuit has to do with the path that current can pass through. Charge flows in a circuit in the direction that current is flowing. Also, resistors in a circuit could be connected in series or in parallel.

In a series connection, the resistors are connected end to end an current flows in one direction.

Thus, the statement that is true is that; In a series circuit, the current can flow through only one path from start to finish.

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Answer: C. In a series circuit, the current can flow through only one path from start to finish.

(just took the test so C is right)

Taking into account the definition of density, you have:

Density is defined as the property that matter has to compress into a given space. That is, density is a quantity that is defined as the amount of mass in a given volume of a substance.

The expression for calculating density is the ratio between the mass of a body and the volume it occupies:

density= mass÷ volume

Density is inversely proportional to volume: the smaller the volume occupied by a given mass, the higher the density.

In this case, you know that:

Replacing in the definition of density:

0.00523 kg/mL= 0.22777 kg÷ volume

Solving:

0.00523 kg/mL× volume= 0.22777 kg

volume= 0.22777 kg÷ 0.00523 kg/mL

volume= 43.55 mL= 0.04355 L (being 1000 mL= 1 L)

Finally, the volume will be 0.04355 L.

In this case, you know that:

Replacing in the definition of density:

density= 5880 mg÷ 1.91 mL

Solving:

density= 3,078.534 mg/mL

Finally, the density of the substance is 3,078.534 mg/mL.

In summary, you have:

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Nanometers is an SI subunit of length equal to 10-⁹ metres. It has a symbol of nm.

The conversion factor of metres to nanometers is as follows:

1 nanometres = 1 × 10-⁹ metres

Hence, 254 nanometers is equivalent to 2.54 × 10-⁷metres.

The frequency of a wave can be calculated using the following formula:

wavelength = wave velocity/frequency

frequency = 3 × 10⁸ ÷ 2.54 × 10-⁷

Frequency = 1.18 × 10¹⁵Hz

Therefore;

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The balanced chemical equation of a reaction between gaseous nitrogen and hydrogen to form gaseous ammonia is as follows; N₂ + 3H₂ → 2NH₃.

A chemical equation is a symbolic representation of a chemical reaction where reactants are represented on the left, and products on the right.

A chemical reaction is said to be balanced, in accordance with the law of conservation of matter, when the number of moles of each atom of elements on both sides of the equation are the same.

According to this question, gaseous nitrogen and hydrogen react to form gaseous ammonia. The balanced chemical equation is as follows:

N₂ + 3H₂ → 2NH₃

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