Answer to this is Radioactive isotopes.
Isotopes are the species of the same element having different atomic masses that means the number of protons remains the same but number of neutrons do differ. For example 
and 
are the two isotopes of Hydrogen (
).
Radioactive isotopes are the isotopes which release some kind of energy in the form of alpha particles, beta particles or gamma radiation. Examples of each of the decay processes are :
Alpha Decay: In this decay one alpha particle having atomic mass 4 and atomic number 2 or we can say a He molecule will come out. 
Beta Decay: In this decay a 
particle is emitted increasing the atomic number of the reactant by 1 unit.
Gamma Radiation: In this type of reaction only radiation is emitted out which does not change the original molecule.
1) reaction coordinate is : <span>b.the plot of the reaction progress as a function of time
2) </span>ΔG⁰ : <span>c.the free energy of the reaction
3) </span>ΔG⁺+ : <span>a.the higher point on the energy curve</span>
Energy diagram for and endothermic and exothermic reaction
Answer:
See explanation
Explanation:
A reaction in which heat and light are produced is a combustion reaction. Combustion is said to have occurred when a substance is burnt in oxygen.
The balanced equation of the reaction is;
4Li(s) + O2(g) ------->2Li2O(s)
This reaction is exothermic because heat was produced. The reaction has a low activation energy as the metal easily burst into flames in oxygen. A catalyst is not needed in this reaction because it has a low activation energy.
According to the law of conservation of mass. Atoms are neither created nor destroyed in a chemical reaction. What this means is that in a chemical reaction, the number of atoms of each element on the left hand side must be the same as the same as the number of atoms of the same element on the right hand side.
B. False
It was created in 1869
