We know this because of the discovery of fossils and bones. We can find out roughly when they existed because of carbon dating.
Neutrons is your answer my friend
Answer : The chronological order events related to the formation of the universe with the stages in which they occurred are given below;
- Expansion from an infinitely hot point - Which is also called as the Planck era from which the big bang theory arrived. It is assumed that from the moment of initial expansion to
seconds afterwards, and many also refer that it was from an infinitely hot point. - Hydrogen fuses into helium - This was called as the era of Nucleosynthesis which resulted from the Fusion and it continued in the Era of Nucleosynthesis ( which is 0.001 seconds – 3 minutes)
- The first neutral atom begins to form - Era of atoms, it began in around 380,000 years – 1 billion years or so.
For better understanding please refer the attachment.
The balanced reaction is:
<span>4 Al + 3 O2
--> 2 Al2O3</span>
Each Aluminum atom wants to lose 3 electrons to become
isoelectronic with Oxygen. Each Oxygen on the other hand wants to gain 2
electrons. Since the reaction shows 6 Oxygen atoms in the product and each want
to gain 2 electrons, therefore a total of 12 electrons are transferred. Since
the problem ask for the electrons transferred per formula unit, hence:
<span>6 electrons (ANSWER)</span>
the correct scientist is rutherford