Answer:
A- Physical, B- Chemical, C- chemical, D- Physical
Explanation:
A is physical because you can see it changing its form is changing.
B is Chemical because a new substance is formed creating the orange color of rust.
C is a Chemical reaction because it is being broken down so the banana itself is changing not just how we see it.
D is physical because we are just changing the shape/ size of the item, not anything to do with its substances.
So to balance an equation, you need to get the same amount of each type of element on either side of the --> . So you pretty much are given the subscripts in the equations and you need to add coefficients (just normal numbers) in front of any formula that needs it, keeping anything balance.

turns into

These coefficient numbers are the molar ratios, so 2 moles of KCl3 for every 3 moles of O2 so 1. 3:2
Then you can use these ratios of find out how many moles of one thing are needed if you are given the amount of another.

and use cross multiplication to solve for whatever you don't know
<span />
The two atoms shown in the equation are CALCIUM and oxygen.
<span>You start off with a neutral calcium atom with a shell of two electrons, a shell of 8 around that, a shell of 8 around that, and a shell containing 2...with no charge. </span>
<span>20 protons + 20 electrons. </span>
<span>You also have an oxygen atom with a shell of 2, and a shell of 6...with no charge. </span>
<span>8 protons + 8 electrons. </span>
<span>Each ionizes to form a calcium ion with 2 electrons removed (from the outer shell), leaving a +2 charge (20 protons, 18 electrons)... </span>
<span>and an oxygen ion with 2 electrons added (to the outer shell), leaving a -2 charge (8 protons, 10 electrons). </span>
<span>Their electrostatic attraction causes them to come together to form an ionic compound of CaO in a crystal lattice.</span>
Answer:
<h3>C6H5CO2H (aq) + H2O (l) _C6H5CO2<em>-</em><em> </em><em>+</em><em> </em><em>H3O</em></h3>