Which answer includes all the following that are chemical changes and not physical changes? I. freezing of water II. rusting of
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Answer : The number of bonding electrons and the number of non-bonding electrons are (4, 18).
Explanation :
The number of bonding electrons and non-bonding electrons in the structure of is determined by the Lewis-dot structure.
Lewis-dot structure : It tell us about the number of valence electrons of an atom within a molecule and it is also shows the bonding between the atoms of a molecule and the lone-pair of electrons.
In the given structure, 'Xe' is the central atom and 'F' is the terminal atom.
Xenon has 8 valence electrons and fluorine has 7 valence electrons.
Total number of valence electrons in = 8 + 2(7) = 22 electrons
From the Lewis-dot structure, we conclude that
The number of electrons used in bonding = 4
The number of electrons used in non-bonding (lone-pairs) = 22 - 4 = 18
Therefore, the number of bonding electrons and the number of non-bonding electrons are (4, 18).
The Lewis-dot structure of is shown below.
Answer : Both solutions contain molecules.
Explanation : The number of molecules of 0.5 M of sucrose is equal to the number of molecules in 0.5 M of glucose. Both solutions contain molecules.
Avogadro's Number is =
which represents particles per mole and particles may be typically molecules, atoms, ions, electrons, etc.
Here, only molarity values are given; where molarity is a measurement of concentration in terms of moles of the solute per liter of solvent.
Since each substance has the same concentration, 0.5 M, each will have the same number of molecules present per liter of solution.
Addition of molar mass for individual substance is not needed. As if both are considered in 1 Liter they would have same moles which is 0.5.
We can calculate the number of molecules for each;
Number of molecules = ;
∴ Number of molecules = which will be =
Thus, these solutions compare to each other in that they have not only the same concentration, but they will have the same number of solvated sugar molecules. But the mass of glucose dissolved will be less than the mass of sucrose.