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ValentinkaMS [17]
3 years ago
5

Даю 90 баллов, помогите

Chemistry
1 answer:
aleksklad [387]3 years ago
5 0

Answer:

MgCO3, Ca(OH)2, AgNO3

Explanation:

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What is a Pure element ?
inn [45]
A substance where almost all have the same atomic number of protons
4 0
3 years ago
Match these items. 1 . Niels Bohr negative charge 2 . n=1 shell basic unit of matter 3 . electron electron path 4 . electron clo
steposvetlana [31]

Answer: Niels Bohr - Drew first picture of atom

n=1 shell - inner orbit

electron - Negative charge

Electron cloud - 3D orbits

Proton - postive charge

Molecule - two or more atoms bonded

Orbit - electron path

John Dalton - Develope atomic theory

Explanation:

1. Niels Borh proposed an atom model taking into account quantum physics. In his model, he proposed that electrons orbit around the nucleus in limited areas and if they need energy to move between orbitals. Although this model has been modified according to recent discoveries, basic postulates remain, that is why is so important the Borh's model

2. n is the principal quantum number which correspond to the orbital of and atom. According to Bohr's model orbits are organized depending on the energy, obits with lower energy are closer to the nucleus and have lower quantum number, so n=1 represent the orbit which closer to the nucleus

3. An electron is a particle of the atom, is the smallest of them and it has negative charge that are attracted by the positive charge of protons, that is why they are orbiting the nucleus.  

4. In modern model there is a principle of uncertainty that states that we can not know the speed and the position of an electron at the same time, so the orbits are consider as spaces or regions where is probable to find and electron. This regions are three dimentional as we conceive the world so they are compare to a cloud with negative charge

5. proton is the partice located in the nucleus of the atom. It was discovered by Rutherford who realized that this particles were attracted to negative charges, and takin into account that different charges attract each other, he concluded that protons have positive charge

6. molecules are the elemental part of a compound and they are made by the two or more atoms that bond through electrons

7 atom is the basic unit of matter because it has particular characteristics according to the number of protons and electrons. This units built all things known in the universe.

8. An orbit was consider by Borh as the path that the electron follows in order to remain closer to the nucleus. He proposed that is was a straigh path as the planets arroud the sun, but nowdays we know that elelctrons are considered in a 3D space that move arround the nucleus.

9. John Dalton is the scientist in modern era that proposed the existence of atoms after studing greek philosophers writings about matter. He proposed that atoms were the smallest unit of matter and the make all the things in nature. Acoording to him, the nature of the electron and the size of it made the diferent elements in the universe. His postulates are very important in science because open a new are of research for chemists and physicists

8 0
3 years ago
I’ve gotten the answer as x=.478 but when plugging back in, .46/.478 ≠ .22. Help please
ivanzaharov [21]

Answer:

15. 2.66 moles .

16. 2.09L.

Explanation:

Molarity of a solution is simply defined as the mole of solute per unit litre of the solvent. Mathematically, it is represented as:

Molarity = mole /Volume.

With the above formula, let us answer the questions given above

15. Data obtained from the question include the following:

Volume of solution = 1.4L

Molarity = 1.9M

Mole of solute =.?

Molarity = mole /Volume

1.9 = mole / 1.4

Cross multiply

Mole = 1.9 x 1.4

Mole = 2.66 moles

Therefore, the mole of the solute present in the solution is 2.66 moles.

16. Data obtained from the question include the following:

Mole of solute = 0.46 mole

Molarity = 0.22M

Volume of solvent (water) =.?

Molarity = mole /Volume

0.22 = 0.46/Volume

Cross multiply

0.22 x Volume = 0.46

Divide both side 0.22

Volume = 0.46/0.22

Volume = 2.09L

Therefore, 2.09L of water is required.

6 0
3 years ago
What is a chemical off of the periodic table that is sticky
Alex73 [517]
I think it’s the one that has a Br
3 0
3 years ago
Read 2 more answers
The rate of effusion of oxygen to an unknown gas is 0.935. what is the other gas?
Kamila [148]

Answer:

N2

Explanation:

Rate of effusion is defined by Graham's Law:  

(Rate 1/Rate 2) = (sqrt (M2)/ sqrt (M1))

(Where M is the molar mass of each substance. )

Molar Mass of oxygen, O2, is 32 (M1).

Rate of effusion of O2 to an unknown gas is .935(Rate 1).  

Rate 2 is unknown so put 1.

Solve for x (M2).

.935/1 = sqrt x/ sqrt32

.935 x sqrt 32 = sqrt x

5.29 = sq rt x

5.29^2 = 27.975 = 28  

N2 has a molar mass of 28 so it is the correct gas.

4 0
3 years ago
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