Answer : The balanced chemical reaction will be,

Explanation :
Balanced chemical reaction : It is defined as the reaction in which the number of atoms of individual elements present on reactant side must be equal to the product side.
If the amount of atoms of each type on the left and right sides of a reaction differs then to balance the equation by adding coefficient in the front of the elements or molecule or compound in the chemical equation.
The coefficient tell us about that how many molecules or atoms present in the chemical equation.
The given chemical reaction is,

This reaction is an unbalanced chemical reaction because in this reaction number of hydrogen bromine atoms are not balanced.
In order to balance the chemical equation, the coefficient '2' put before the
and we get the balanced chemical equation.
The balanced chemical reaction will be,

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:
c) both
Explanation:
hey, could you check the question once because I suppose it's 2-hexyne when there's a triple bond and 2-hexene when there's a double bond between Carbon atoms. As of the question asked, it's c) both but it's 2-hexene due to presence of double bond between Carbon atoms.
do tell me as well. have a good day :-))