<h3>Answer:</h3>
<u>Breaking</u> chemical bonds requires energy and <u>forming</u> chemical bonds releases energy.
<h3>Explanation:</h3>
Bond Breaking is an endothermic reaction and requires energy. This energy provided to break the bond is called as bond energy. Hence, this is a non spontaneous reaction as it doesn't takes place on its own but requires energy to break them into smaller fragments.
While, Bond Forming is an exothermic reaction. When two substances come close together the formation of bond results in the release of energy. As the resulting product is stable hence, it will be lower in energy as compared to the sum of energies of the reactants. Therefore, the surplus energy is released in the form of heat.
Answer:
MnCO3 + 2H2O ⇄ MnO2 + HCO3- + 2e- +3H+
Explanation:
<u>The</u> unbalanced equation
MnCO3 ⇄ MnO2 + HCO3-
In MnCO3, the oxidation number of Mn is +2
In Mno2, the oxidation number of Mn is +4
The change from +2 to +4 requires an addition of 2 electrons (to the right side).
MnCO3 ⇄ MnO2 + HCO3- + 2e-
The total charge now is -3 on the right side. To balance this we add 3 hydrogen atoms on the right side.
MnCO3 ⇄ MnO2 + HCO3- + 2e- +3H+
On the right side we have 4 hydrogen atoms in total. On the left side we have 0 hydrogen atoms. So to balance, we have to add 2H2O on the left side
MnCO3 + 2H2O ⇄ MnO2 + HCO3- + 2e- +3H+
Now the reaction is balanced.
D.
because that can only be the answer
Answer: Aluminium
Explanation: Aluminium metal has a lower density than copper. So, for the same volume of metal used to build a model airplane, the aluminium plane would be very lightweight while that of copper would be heavy. The lightweight airplane will fly easily.
