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ioda
3 years ago
7

How is a pure substance different from a mixture? A. pure substances cannot be seperated by physical means.

Chemistry
2 answers:
Firdavs [7]3 years ago
7 0

Answer:

How is a mixture different from a pure substance?

Mixtures can be separated by physical means.

Explanation:

jeyben [28]3 years ago
6 0

Answer: Pure substances cannot be separated by physical means.

Explanation:

A pure substance is a substance which contains definite composition of only one type of component. Hence, it cannot be separated by physical means.

On the other hand, a mixture is a substance which contains two or more than two types of components and they can be separated by physical means as well.

Thus, option (a) is correct one that is pure substances cannot be separated by physical means.

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state the conditions under which copper reacts with sulphuric (vi) acid and give an equation for the reaction​
uranmaximum [27]

Answer:

When the metal reacts with hot, concentrated sulphuric acid, the products of the reaction are copper (II) sulphate, sulphur dioxide and water. Cu + 2H2SO4 = CuSO4 + SO2 + 2H2O. This is a typical redox reaction in which the acid is reduced to SO2, but no hydrogen is produced here

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2 years ago
The amount of matter in an object is its
andrezito [222]

The amount of matter in an object is its Mass...

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2 years ago
Rank the following elements by effective nuclear charge, Zeff, for a valence electron. F LI Be B N
Stels [109]

Answer:

Rank in increasing order of effective nuclear charge:

  • Li < Be < B < N < F

Explanation:

This explains the meaning of effective nuclear charge, Zeff, how to determine it, and the calculations for a valence electron of each of the five given elements: F, Li, Be, B, and N.

<u>1) Effective nuclear charge definitions</u>

  • While the total positive charge of the atom nucleus (Z) is equal to the number of protons, the electrons farther away from the nucleus experience an effective nuclear charge (Zeff) less than the total nuclear charge, due to the fact that electrons in between the nucleus and the outer electrons partially cancel the atraction from the nucleus.

  • Such effect on on a valence electron is estimated as the atomic number less the number of electrons closer to the nucleus than the electron whose effective nuclear charge is being determined: Zeff = Z - S.

<u><em>2) Z eff for a F valence electron:</em></u>

  • F's atomic number: Z = 9
  • Total number of electrons: 9 (same numer of protons)
  • Period: 17 (search in the periodic table or do the electron configuration)
  • Number of valence electrons:  7 (equal to the last digit of the period's number)
  • Number of electrons closer to the nucleus than a valence electron: S = 9 - 7 = 2
  • Zeff = Z - S = 9 - 2 = 7

<u><em>3) Z eff for a Li valence eletron:</em></u>

  • Li's atomic number: Z = 3
  • Total number of electrons: 3 (same number of protons)
  • Period: 1 (search on the periodic table or do the electron configuration)
  • Number of valence electrons: 1 (equal to the last digit of the period's number)
  • Number of electrons closer to the nucleus than a valence electron: S = 3 - 1 = 2
  • Z eff = Z - S = 3 - 2 = 1.

<em>4) Z eff for a Be valence eletron:</em>

  • Be's atomic number: Z = 4
  • Total number of electrons: 4 (same number of protons)
  • Period: 2 (search on the periodic table or do the electron configuration)
  • Number of valence electrons: 2 (equal to the last digit of the period's number)
  • Number of electrons closer to the nucleus than a valence electron: S = 4 - 2 = 2
  • Z eff = Z - S = 4 - 2 = 2

<u><em>5) Z eff for a B valence eletron:</em></u>

  • B's atomic number: Z = 5
  • Total number of electrons: 5 (same number of protons)
  • Period: 13 (search on the periodic table or do the electron configuration)
  • Number of valence electrons: 3 (equal to the last digit of the period's number)
  • Number of electrons closer to the nucleus than a valence electron: S = 5 - 3 = 2
  • Z eff = Z - S = 5 - 2 = 3

<u><em>6) Z eff for a N valence eletron:</em></u>

  • N's atomic number: Z = 7
  • Total number of electrons: 7 (same number of protons)
  • Period: 15 (search on the periodic table or do the electron configuration)
  • Number of valence electrons: 5 (equal to the last digit of the period's number)
  • Number of electrons closer to the nucleus than a valence electron: S = 7 - 5 = 2
  • Z eff = Z - S = 7 - 2 = 5

<u><em>7) Summary (order):</em></u>

  Atom          Zeff for a valence electron

  • F                   7
  • Li                   1
  • Be                 2
  • B                   3
  • N                   5

  • <u>Conclusion</u>: the order is Li < Be < B < N < F
6 0
3 years ago
What is the chemical formula for 2-propanol?
monitta

i think the answer is  C3H8O

8 0
3 years ago
Silver is a white metal that is an excellent conductor. Silver tarnishes when exposed to air and light. The density of silver is
Stells [14]

Answer:

c tarnishes in air

Explanation:

After silver has been exposed to air that contains sulphur gases, discoloration would occur. there would be darkening that is caused by the reaction with gases.When any silver object tarnishes, it brings about a disfiguring of that object. Hydrogen sulphide would be needed for this to happen. silver sulphide is black and a if a thin layer should form on any surface, it ill darken it. This  is what we refer to as tarnishing.

3 0
3 years ago
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