Answer:
mole fraction of NaCl = 0.03145.
mole fraction of water = 0.9686.
Explanation:
- Mole fraction is an expression of the concentration of a solution or mixture.
- It is equal to the moles of one component divided by the total moles in the solution or mixture.
- The summation of mole fraction of all mixture components = 1.
mole fraction of NaCl = (no. of moles of NaCl) / (total no. of moles).
<em>no. of moles of NaCl = mass/molar mass </em>= (6.87 g)/(58.44 g/mol) = 0.1176 mol.
<em>no. of moles of water = mass/molar mass</em> = (65.2 g)/(18.0 g/mol) = <em>3.622 mol.</em>
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∴ mole fraction of NaCl = (no. of moles of NaCl) / (total no. of moles) = (0.1176 mol)/(0.1176 mol + 3.622 mol) = 0.03145.
<em>∵ mole fraction of NaCl + mole fraction of water = 1.0.</em>
∴ mole fraction of water = 1.0 - mole fraction of NaCl = 1.0 - 0.03145 = 0.9686.
Answer:
Option C. The same number of energy levels.
Explanation:
From the diagram given above, element (i) belong to group 2 while element (ii) belong to group 6.
Also, both element i and ii belong to the same period (i.e period 4). This simply means that both element i and ii have the same number of energy levels.
NOTE: Elements in the same period have the same number of shells of electrons which simply means they have the same energy levels.
Answer: The correct statement is (A new substance is formed and the process can usually NOT be undone.)
Explanation:
A chemical reaction is simply defined as the reaction between two or more elements in which a new substance is formed and the process can usually not be undone. Different types of chemical reaction includes:
-- combination reaction: this occurs when two or more reactants form a product. For example: In the burning of coal, It combines with oxygen to produce carbon dioxide. Also in the burning of wood, carbon dioxide is given off and ashes are formed. Because new substance is being formed, they often can't be undone. The ashes formed can't be changed back into wood. Other types of chemical reaction are listed below.
-- Decomposition reaction
-- Single displacement reaction
-- Double displacement reaction
-- combustion reaction
-- Redox reaction
For the product of a chemical reaction to be undone (reversed), it has to undergo another chemical process different from the one that produced it.
This was an answer i found on google from Nasa
The correct number of significant figures and digits is 3
