The isotope notation : 
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Further explanation
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Given
53 protons and 20 neutron
Required
The isotope notation
Solution
Isotopes are elements that have the same atomic number with a different mass number
The following element notation,

X = symbol of element
A = mass number
= number of protons + number of neutrons
Z = atomic number
= number of protons = number of electrons, on neutral elements
So the mass number of element = 5 + 6 11
Atomic number = 5
The symbol :

I would say fall/ autumn in South America because they are in opposite hemispheres.
its exothermic. exothermic means the reaction gives out heat. [exo meaning outside and thermic meaning heat] because its a combustion reaction, fire is there meaning lots of heat.
endothermic means it takes in heat. a good example is ammonium and water (NH3 +H20)
<span>most chemical reaction are exothermic</span>