Select all the correct answers. Which sentences describe an advantage of using a hydrogen fuel cell instead of burning fossil fuels?​

Answer:

207.2

Explanation:

One mole of lead weighs 207.2 g. Thus, number of moles in 454 g of lead is determined by dividing the given mass by atomic mass that is ., 2.19 moles.

Lead is 82nd element in periodic table. It is in 14th group. Lead is classified among non-metals but it is a heavy metal in nature. Lead have many naturally stable isotopes of which two are radioactive.

A substance containing 6.02 × 10²³ atoms is called its one mole. This number is called Avogadro number. Hence, one mole of every elements contains Avogadro number of atoms. The mass of one mole of an element is called its atomic mass.

Atomic mass of lead (Pb) = 207. 2 g/mol

thus, number of moles in 454 g of Pb = given mass/atomic mass

no.of moles = 454 /207.2 = 2.19 moles.

Therefore, the number of moles of Pb in 454 g is 2.19.

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Answer:

First Energy Level: 2

Second Energy Level: 8

Third Energy Level: 18

Fourth Energy Level: 18

Element: Iodine

Group: 17

No. of electrons/shell: 2, 8, 18, 18, 7

Answer:

C=C divided by the co effiecient 11 would make the denominator of the photosynthesis equal 11 over 5 making this problem a polywhirl which wouldnt matter in the sense of the quake in energy change so thus making the answer 728 kJ/mol

Explanation: back in my day

Answer:
1. [tex]x=4[/tex]
2.[tex]x=\frac{57}{7}[/tex]
3.[tex]x=\frac{27.7}{11}[/tex]

Explanation:

Given the following questions:

[tex]12=3x[/tex]
[tex]7x=57[/tex]
[tex]11x=27.7[/tex]

In order to find the answers to these questions, we have to recognize that in order to isolate the variable we need to divide on both sides.

Question one:
[tex]12=3x[/tex]
[tex]\frac{3x}{3} =\div3[/tex]
[tex]12\div3=4[/tex]
[tex]x=4[/tex]

Question two:
[tex]7x=57[/tex]
[tex]\frac{7x}{7} =\div7[/tex]
[tex]57\div7=8.14285714=\frac{57}{7}[/tex]
[tex]x=\frac{57}{7}[/tex]

Question three:
[tex]11x=27.7[/tex]
[tex]\frac{11x}{11} \div11[/tex]
[tex]27.7\div11=2.51818182=\frac{27.7}{11}[/tex]
[tex]x=\frac{27.7}{11}[/tex]

Hope this helps.

Explanation:

I answered your question in the submitted photo

An organism that is well-suited for living in the tundra ecosystem should ideally be adapted to cold conditions. These organisms should take advantage of the growing season and survive in low humidity conditions.

Tundra is a special type of ecosystem characterized by low temperatures, a short growing season, and low humidity.

In consequence, any organism (either plant or animal) living in a tundra should exhibit adaptation to these climate conditions.

For example, plants in the tundra are able (i.e., they are adapted) to perform photosynthesis in extremely cold temperature conditions.

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Answer:

- breaking it down into sections

-learn the element song

-use colors to learn the element groups

Explanation:

what also may help which is time-consuming is writing it out over and over if not I would prefer to learn the song it may seem childish a little but it will help in the long run.

Answer:

I personally have a method for learning stuff like this.

Try going one at a time, and ever once in awhile. Like memorize the first element, then the one next to it [in whichever order you please]

Ex: memorizing 1-10

1.. 1,2.. 1,2,3.. 1,2,3,4..

And then repeat that row until you can recite it almost without hesitation, then move onto another line.

This works for both placement memorization and element name.

Explanation:

It is the safest way to shut down a circuit by switching off the main switch. If you haven't switched off the main switch and started directly working on it you are open to all kinds of harm one being electrocuted (since high current flows through the electric circuits due to the short circuit or overloading, the fuse wire heats and melts down) other methods of avoiding being electrocuted after turning the main switch off is by using insulating tools such as tools made of wood.

Answer:

electromagnetic waves

Explanation:

Radiation is the transfer of heat energy through space. Most of them are sent through electromagnetic waves.

Answer:

A (2.475 mol O2). B (11.35 g)  C. (.4875 mol O2)

Explanation:

A.

convert 25.9 g C4H10 (68g/mol) to mol. --> .3808 mol

then use mole ratios from equation

.3808 mol C4H10 x (13 mol O2 / 2 mol C4H10). ---> 2.475 mol O2

B.

convert 22.2 g CO2 (44g/mol) to mol. ---> .5045 mol

.5045 mol CO2 x (10 mol H2O / 8 mol CO2) ----> .6306 mol H2O

convert .6306 mol to g ----> 11.35 g

C.

.3 mol CO2 x (13 mol O2 / 8 mol CO2) ---> .4875 mol O2

When the blood pH increase from the normal, carbonic acid is the chemical which neutralize it.

We know that acid neutralizes base whereas base neutralize acid. In the blood, bicarbonate ion is responsible to neutralize acid.

While on the other hand, bases in the blood increase the pH which are neutralized by carbonic acid (H2CO3) so we can conclude that carbonic acid neutralizes increase pH of the blood.

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Answer:

D. tap water

keep on learning!

Answer: ethanol

Explanation: as it is a pure compound and can sometimes be a mixture while all the rest are mixtures.

The partial pressure is the pressure exerted by individual gas in the mixture. The total pressure of the tank is 5.95 atm.

According to the Dalton's law of vapor pressure, the total pressure of the gas is the sum of the partial pressure of individual gas in the mixture.

The tank has mixture of nitrogen and oxygen gas. The partial pressure of nitrogen gas ([tex]P_{N_2}[/tex]) is 1.61 atm, and the partial pressure of oxygen ([tex]P_{O_2}[/tex]) is 4.34 atm.

The total pressure of tank ([tex]P[/tex]) according to Dalton's law can be given as:

[tex]P=P_{N_2}+P_{O_2}\\P=1.61+4.34\;\rm atm\\\textit P=5.95\;atm[/tex]

The total pressure of the tank is 5.95 atm.

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The Triassic period is one of the geological periods and is the shortest of the Mesozoic era. Cambrian is the older era than the Triassic period.

The Triassic period existed 250 -200 million years ago and started after the vastest and most extreme devastation ever. It is the 1st period of the Mesozoic and is known for the movement of the Dinosaurs on the land, flying pterosaurs and swimming plesiosaurs and ichthyosaurs.

The Cambrian is the period of the Paleozoic era and is the most important period because of the appearance of many animals. In this period, the temperature raised on the planet and the ice sheets melted at a very dangerous rate leading to mass devastation.

Therefore, option A. Cambrian is older than the Triassic period.

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Answer:

A: Cambrian!

Explanation:

got it right on ed :)

K^+ can not exists because electrons are removed from an inner shell. The ion O^- can not exist because it will have an incomplete octet.

Ions are species that contain a positive or a negative charge. When we consider the electron configuration of ions, we can deduce the stability of the ion.

Let us consider the electron configuration of K^2+ which is 1s2 2s2 2p6 3s2 3p5 which means that the second electron is to be removed from an inner shell which implies greater energy expenditure hence it does not exist.

In the case of O^-, involves the formation of an ion with an incomplete octet which is not possible.

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Animals can produce sound by vibration of air in their vocal chords as in flutes and trumpets.

Animals can also produce sound by clicking body parts together as cymbals and tambourine.

Sound is a form of energy that produces a vibration of air particles which can be heard by the ear.

Sound can either be produced by

Animals such as dogs produce sound be making are to vibrate in their vocal chords as in wind instruments like trumpets and flutes.

Animals such as some birds can also produce sound by clicking body parts together just as in cymbals and tambourine.

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Answer: 22.4 L

Explanation:

the constant for one mol of gas at STP is always 22.4 L and this constant is used in equations when converting from L to mol or mol to L

hope this helps :)

The equation that depicts a single replacement reaction would be: Zn(s) + 2HCl(aq)→ ZnCl2​​​(aq) ​​​​+ H2(g)

They are also known as single displacement reactions.

They are reactions in which one element takes the place of another in a compound. That is, one element replaces another in a compound.

Looking at all the reactions from A - D, one can see that the only reaction that exemplifies a single replacement reaction is D.

Here, Zn replaced H in HCl.

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Yes it is but I have to check so wait

For this buffered solution with a pH of 7.5, B. The pH would become less than 7.0.

In Science, pH literally means the power of hydrogen ions and it can be defined as a measure of the molar concentration of hydrogen ions in a particular solution. Thus, it is typically used to specify the acidity, neutrality or basicity of any chemical solution.

On a pH scale, a solution with a pH of 7 is neutral while a solution with a pH below 7 is acidic and it's basic (alkaline) when its pH is above 7.

In this scenario, a buffered solution with a pH of 7.5 would become less than 7.0 when a small amount of acid is added to it.

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Answer:

carbon dioxide and water

Explanation:

The process by which plants make their food with the help of water, carbon dioxide, sunlight and convert it into sugar and provides energy to the plant.

Hope it helps you.

Stay safe, stay healthy and blessed.

Have a great day !

Thank you

Answer:

To calculate the percent composition, we need to know the masses of C, H, and O in a known mass of C9H8O4. It is convenient to consider 1 mol of C9H8O4 and use its molar mass (180.159 g/mole, determined from the chemical formula) to calculate the percentages of each of its elements:

%

C

9

mol C

×

molar mass C

molar mass

C

9

H

18

O

4

×

100

=

9

×

12.01

g/mol

180.159

g/mol

×

100

=

108.09

g/mol

180.159

g/mol

×

100

%

C

60.00

%

C

Answer:

give answer of following questions and get 35 points.

Answer:

As the planets mass distribution around the sun changes, the point which the planets orbit changes slightly, disrupting any circular orbits

Explanation:

Answer:

because postulates that the force of gravity weakens as the square of the distance between the two objects

Explanation:

pls mark as brailliest

Answer: 0.16 M

Explanation:

molarity is a way to measure the concentration of solutions, the equation is the amount of solute in mol / liter of solution:

mol (solute) / L (solution)

the first thing you want to do is convert grams to moles:

20g NaF • 1 mol

———— = 0.47632464 mol

41.98817 g (molar mass of NaF)

then you just want to follow with the rest of the equation:

0.47632464 mol NaF / 3.0 L = 0.15877488 or 0.16 M (sigfigs)

hope this helps :)

Answer:

Carbon is never really lost in the cycle. Carbon is constantly added and removed from the carbon cycle. Example.....  Carbon dioxide is removed from the air by photosynthesis and dissolving in the ocean buttttt at the same time it is added to the atmosphere by respiration and combustion.

As for the mass and energy....the Law of Conservation of Matter states that matter cannot be created or destroyed.

Answer:

no its not ever lost

Explanation:

The temperature that must be to freeze the solution would be -21.1 ° C.

To calculate the freezing temperature we must take into account the following information.

According to the above, it can be inferred that the puddle has a 50% concentration of salt because they had 12 kg of water and 6 kg of salt.

So the lowest freezing temperature would be 21.1°C because the puddle is 50% concentrated.

Note: This question is incomplete because there is some missing information. Here is the missing information:

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Particles are the smallest units of any state of matter that moves in a medium due to various factors. The particle movement best supports the collision theory.

In a reactant, the particles move and collide with each other resulting in some amount of change and the collision between the atoms and the molecules are necessary for a chemical reaction to occur.

This theory of collision is used for the prediction of the rate of the reaction to occur and the chemical changes occurring in a gas or the reactant. This aids in understanding the rate of reaction occurring in a system.

The collision of the particles is proportional and related to the rate of the reaction. The amount of the concentration and their collision affects the rate at which the chemical change will occur.

Therefore, option A. the collision theory is supported here.

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