A thermochemical reaction is a chemical reaction with an additional information of the heat of reaction. For example, this is the thermochemical reaction for the combustion of hydrogen gas:
H₂ (g) + 1/2 O₂ (g) → H₂O (l) ΔH = -285.8 kJ
The coefficient 1/2 represents the number of moles of O₂ needed to combust 1 mole of H₂ gas in order to yield one mole of water.
Explanation:
from the graph study about oxygen content of Earth's atmosphere, we can understand that
1)
4 billions year ago = None, 3 billions year ago = Cyanobacteria and Archaea , 2 and 1 billions year ago = Bacteria and Green algae , 500 Ma = invertebrate fossils started to existence. Early land plants came in to existence around 398 MA that is Devonian. Dinosaurs are came in to existence during Triassic and Jurassic that is around 251 Ma. Man and animals are recent organism came under Holocene that is 11000 years ago.
2)
The first cells on the earth are anaerobic microorganisms, as the CO2 level is too high they survive by using CO2.
3)
Starting around 2.7 billion years ago, photosynthesis by Cyanobacteria and later plants , pumped “OXYGEN” in to the atmosphere. This caused the decline of anaerobic bacteria and allows the diversification of animals as seen in “CAMBRIAN” around 500 millions year ago.
Early vascular plants “CAPTURED” CO2 starting before the Carboniferous period that began around 350 millions year.Leading to lower temperatures and allowing and allowing the seed plants to outcompetes seedless plants.
Modern human activities has raised both “CO2 and METHANE” level in the atmosphere to over leading to higher temperature and extinction of other species.
Answer:
10
Explanation:
In image
Take atomic mass or molar mass
of Al =27
The number that represents the coefficient on the product side of the chemical reaction, 
is 7.
<h3>Coefficients of chemical equations</h3>
In equations representing chemical reactions, the coefficient of each reactant or product of a reaction is the number that comes on the left-hand side just before the chemical formula.
The coefficient of each species in a chemical reaction is obtainable when the equation of the reaction is balanced.
For example, in the following equation: 2A + B = 3C + D
The coefficients of A, B, C, and D are 2, 1, 3, and 1 respectively.
Applying this to the product side of a chemical reaction;
It means that the coefficient of the product is 7.
More on coefficients of chemical equations can be found here: brainly.com/question/28294176
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