True
These are all indicators of a chemical change.
<h2>Al (s) + O₂ (g)----> Al₂O₃(s)</h2>
Explanation:
Chemical reaction
When two or more substances react and form some new substance it is called as chemical reaction .
For example :
Al (s) + O₂ (g)----> Al₂O₃(s)
Chemical equation
It is the representation of chemical reaction in terms of symbols ,molecular formulas ,moles , states etc .
As we know all chemical reaction obeys law of chemical combination therefore chemical reaction need to be balanced .
Law of conservation of mass
Mass can neither be created nor be destroyed in a chemical reaction , it is always conserved .That is why reactions need to be balanced .
Let us balance
Al (s) + O₂ (g)----> Al₂O₃(s)
After balancing , it becomes :
2Al (s) + 3/2O₂ (g)----> Al₂O₃(s)
<h3><u>Answer;</u></h3>
only in the n = 3 energy level
<h3><u>Explanation;</u></h3>
- <em><u>The atom of a chemical element is made up of sub-atomic particles which are the neutrons, protons and electrons.</u></em> The neutrons and protons occupies the nucleus of an atom while the electrons occupy the energy levels.
- <em><u>The first energy level (n=1) of an atom occupies a maximum of two electrons because it has only an S-orbital which can only have two electrons.</u></em>
- <u>The second energy level (n=2) can have a maximum number of 8 electrons, since it contains, one S- orbital which can hold two electrons, and a p-orbital which can accommodate six electrons.</u>
- <em><u>The third energy level (n=3) can have a maximum number of 18 electrons,</u></em> because it has <u><em>the S-orbitals which holds 2 electrons, the p-orbital which holds 6 electrons and the d-orbital which holds 10 electrons. </em></u>
The balanced chemical reaction is expressed as:
3HCl + Al(OH)3 = AlCl3 + 3H2O
We are given the amount of aluminum hydroxide to be used up in the reaction. This value will be the starting point for the calculations. We calculate as follows:
1.55 g Al(OH)3 ( 1 mol Al(OH)3 / 78 g Al(OH)3 )( 3 mol HCl / 1 mol Al(OH)3 ) = 0.06 mol HCl
Volume = 0.06 mol HCl / 0.120 mol HCl/ L solution = 0.50 L solution
