Volume = (4/3) × π × r^3
R = 1/2 D
R = 7
V = 4/3 x π x 7^3
Exact Form:
1372 π/ 3
Decimal Form:
1436.75504024
Number of moles : n₂ = 1.775 moles
<h3>Further explanation</h3>
Given
Moles = n₁ = 1.4
Volume = V₁=22.4 L
V₂=28.4 L
Required
Moles-n₂
Solution
Avogadro's hypothesis, at the same temperature and pressure, the ratio of gas volume will be equal to the ratio of gas moles
The ratio of gas volume will be equal to the ratio of gas moles

Input the values :
n₂ = (V₂ x n₁)/V₁
n₂ = (28.4 x 1.4)/22.4
n₂ = 1.775 moles
Answer: Air
Hope this helps
Identical electron configurations : K⁺ and Cl⁻
<h3>Further explanation </h3>
In an atom, there are levels of energy in the shell and sub-shell
This energy level is expressed in the form of electron configurations.
Charging electrons in the sub-shell uses the following sequence:
<em>1s², 2s², 2p⁶, 3s², 3p⁶, 4s², 3d¹⁰, 4p⁶, 5s², 4d¹⁰, 5p⁶, 6s², etc. </em>
S²⁻ : [Ne] 3s²3p⁶
Cl : [Ne] 3s²3p⁵
K⁺ : 1s² 2s² 2p⁶ 3s² 3p⁶
Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶
S :[Ne] 3s²3p⁴
Ar : [Ne] 3s²3p⁶
Cl⁻ : 1s² 2s² 2p⁶ 3s²3p⁶
K : 1s² 2s² 2p⁶ 3s² 3p⁶4s¹
Answer:
- <em>He realized that some elements had not been discovered.</em>
Explanation:
Some scientists that tried to arrange the list of elements known before Mendeleev include Antoine Lavoisier, Johann Döbereiner, Alexandre Béguyer de Chancourtois, John Newlands, and Julius Lothar Meyer.
<em>Dimitri Mendeleev</em> was so succesful that he is recognized as the most important in such work.
Mendeleev by writing the properties of the elements on cards elaborated by him, and "playing" trying to order them, realized that, some properties regularly (periodically) repeated.
The elements were sorted in increasing atomic weight (which is not the actual order in the periodic table), but when an element did not meet the pattern discovered, he moved it to a position were its properties fitted.
The amazing creativity of Mendeleev led him to leave blanks for what he thought were places that should be occupied by elements yet undiscovered. More amazing is that he was able to predict the properties of some of those elements.
When years after some of the elements were discovered, the genius of Mendeleev was proven because the "new" elements had the properties predicted by him.