HELP ME ASAP PLZZ 21 POINTS

Answer:

76

Explanation:

Mass number = number of protons plus the number of neutrons

So, 36 + 40 = 76

what element is A??????

Answer: less oxygen available at higher altitudes

Explanation:

The higher in elevation you get, the lower the air pressure, allowing oxygen atoms to spread out farther, therefore making available oxygen less.

Answer:

The rainforest is teeming with animals and insects, so you would hear  humming. Frogs and birds make some of the loudest rainforest sounds.

howler monkeys, are the loudest so i think that its false cause lost of animals are there but some can be quiet

Answer:

Evaporating the solvent

Explanation:

Answer:

50 moles

Explanation:

took the quiz

Answer:

The mass of carbon dioxide formed is 12g.

I did not see any errors, i may be wrong but what i can see is that it is correct

Answer:

they have the same structures in common

Answer:

Rewrite the following sentence in reported speech

The chair person said,"A hearty welcome to all present!"

Answer: [tex]H_2SO_4[/tex] is the limiting reagent.

Explanation:

A double displacement reaction is one in which exchange of ions take place. The salts which are soluble in water are designated by symbol (aq) and those which are insoluble in water and remain in solid form are represented by (s) after their chemical formulas.  

The balanced chemical equation is:

[tex]3H_2SO_4(aq)+2Al(OH)_3(aq)\rightarrow Al_2(SO_4)_3(aq)+6H_2O(l)[/tex]

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} H_2SO_4 =\frac{30g}{98g/mol}=0.31moles[/tex]

[tex]\text{Moles of} Al(OH)_3=\frac{25g}{78g/mol}=0.32moles[/tex]  

According to stoichiometry :

3 moles of [tex]H_2SO_4[/tex] require = 2 moles of [tex]Al(OH)_3[/tex]

Thus 0.31 moles of [tex]H_2SO_4[/tex] will require=[tex]\frac{2}{3}\times 0.31=0.21moles[/tex]  of [tex]Al(OH)_3[/tex]

Thus [tex]H_2SO_4[/tex] is the limiting reagent as it limits the formation of product and [tex]Al(OH)_3[/tex] is the excess reagent.

Answer: A mole is a chemical unit to measure mass of substance.

Explanation:

A mole can be defined as 6.02214076 × 1023 of atoms, ions, molecules and others. A mole is the total amount of discrete entity within a substance present in the form of atoms, ions, and molecules. As atoms, ions, molecules are small entities within any substance so it is necessary to measure each of them and recognize them so the scientists development the concept of mole. It is the convenient unit of measurement because of the presence of greater number of molecules, atoms, and ions present in any substance.

Answer:

The mole is an SI unit used to measure the amount of any substance. One mole is exactly 6.02214076×10 23 particles.

Explanation:

The concept of the mole is important for scientists because it means that one mole of any element has exactly the same number of atoms as one mole of any other element. This information allows chemists to count atomic particles for even very complex chemistry formulas and reactions.

Answer: 16.32 g of [tex]O_2[/tex] as excess reagent are left.

Explanation:

To calculate the moles :

[tex]\text{Moles of solute}=\frac{\text{given mass}}{\text{Molar Mass}}[/tex]    

[tex]\text{Moles of} SO_2=\frac{21.71g}{64g/mol}=0.34mol[/tex]

[tex]\text{Moles of} O_2=\frac{21.71g}{32g/mol}=0.68mol[/tex]

[tex]2SO_2(g)+O_2(g)\rightarrow 2SO_3(g)[/tex]  

According to stoichiometry :

2 moles of [tex]SO_2[/tex] require = 1 mole of [tex]O_2[/tex]

Thus 0.34 moles of [tex]SO_2[/tex] will require=[tex]\frac{1}{2}\times 0.34=0.17moles[/tex]  of [tex]O_2[/tex]

Thus [tex]SO_2[/tex] is the limiting reagent as it limits the formation of product and [tex]O_2[/tex] is the excess reagent.

Moles of [tex]O_2[/tex] left = (0.68-0.17) mol = 0.51 mol

Mass of [tex]O_2=moles\times {\text {Molar mass}}=0.51moles\times 32g/mol=16.32g[/tex]

Thus 16.32 g of [tex]O_2[/tex] as excess reagent are left.

Answer:

21

Explanation:

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The wave which is having higher frequency is associated with higher energy. In the given wave, the part B is labelling the lowest energy sound.

Sound waves are longitudinal mechanical waves passing through a medium. In a longitudinal wave the oscillation of particles is in a direction along the wave propagation.

A sound wave is composed of rarefactions and compressions. The area where, the particles have some separation with lower  pressure is called rarefactions.

The area of high pressure where, the oscillating particles are closely packed is called compression of the wave. As the frequency of the wave increases, its energy increases, Therefore, the less frequency part B represent lowest energy sound.

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Answer:

Correct

Explanation:

According to the balanced chemical reaction, 2 mol FeBr3 are consumed for every 3 mol Na2S consumed.

A balanced equation obey the law of conservation of mass. The coefficients are the numbers which are added to balance the chemical equation. Here the given mole ratio is correct.

An equation in which the number of atoms of reactants and products on both sides of the equation are balanced is defined as the balanced chemical equation. The coefficients which are added in front of the formula of each component represents the number of the species.

A molar ratio denotes the ratio between the amounts in moles of any two compounds involved in a balanced chemical reaction. By comparing the coefficient of each component, the mole ratio can be determined.

Here for the given reaction, for every 3 moles of Na₂S consumption 2 moles of FeBr₃ is also consumed. So the molar ratio of Na₂S to FeBr₃ is 2/3. Molar ratios are used as the conversion factors between products and reactants in many chemistry problems.

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Answer:

10.57% of N in acetanilide

Explanation:

All nitrogen in the sample is converted in NH₃ in the Kjeldahl determination. The NH₃ reacts with H₂SO₄ as follows:

2NH₃ + H₂SO₄ → 2NH₄⁺ + SO₄²⁻

The acid in excess in titrated with Na₂CO₃ as follows:

Na₂CO₃ + H₂SO₄ → Na₂SO₄ + H₂O + CO₂

To solve this question we must find the moles of sodium carbonate = Moles of H₂SO₄ in excess. The added moles - Moles in excess = Moles of sulfuric acid that reacts:

Moles Na₂CO₃ anf Moles H₂SO₄ in excess:

0.025L * (0.05mol / L) = 1.25x10⁻³ moles Na₂CO₃ / 0.01360L =

0.09191M * 0.250L = 0.0230 moles H₂SO₄ in excess.

Moles H₂SO₄ added:

0.050L * (0.50mol / L) = 0.0250 moles H₂SO₄ added

Moles that react:

0.0250 moles - 0.0230 moles = 0.0020 moles H₂SO₄

Moles of NH₃ = Moles N:

0.0020 moles H₂SO₄ * (2mol NH₃ / 1mol H₂SO₄) = 0.0040 moles NH₃ = Moles N

mass N and mass percent:

0.0040 moles N * (14g / mol) = 0.056gN / 0.53g * 100 =

Answer:

Ecosystem

Explanation:

The answer is ecosystem because the ecosystem includes the community such as living things and the enviornment of nonliving things such as the sun!

Answer:

ecosystem I'm pretty sure

Answer:

true

Explanation:

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Answer:

When these chemical bonds form, atoms of some elements have a greater ability to attract the valence electrons involved in the bond than other elements. Electronegativity is a measure of the ability of an atom to attract the electrons when the atom is part of a compound. Electronegativity differs from electron affinity because electron affinity

HOPE IT HELPS

Explanation:

Answer:

it is electronegativity and it increases as you move up and to the right on the periodic table and nonmetals are situated to the top right of the periodic table

Explanation: