Questions

A redox reaction is a type of reaction which involves transfer of electrons among two species. This reaction is also called oxidation-reduction reaction.

In oxidation process, there is an increase in oxidation state of an atom, ion or molecule by losing the electrons.

In reduction process, there is a decrease in oxidation state of an atom, ion or molecule by accepting the electrons.

1)

In this reaction, Ba undergoes oxidation and Cl undergoes reduction.
This reaction is redox reaction.
In this reaction, oxidation number of Ba increases from 0 to +2 . So, Ba undergoes oxidation. The oxidation number of Cl decreases from 0 to -1. So, Cl undergoes reduction.

2) 

From this above reaction, it is clear that Aluminum undergoes oxidation and silver undergoes reduction.
Due to this, this reaction is redox reaction.

In this reaction, oxidation number of Aluminum increases from 0 to +1. So, aluminum undergoes oxidation. The oxidation number of silver decreases from +1 to 0. So, silver undergoes reduction.

3)

In this reaction, Mg undergoes oxidation and Br undergoes reduction.
This reaction is redox reaction.
The reactions 1, 3 and 4 are redox reactions.
In this reaction, oxidation number of Mg increases from 0 to +2 . So, Mg undergoes oxidation. The oxidation number of Br decreases from 0 to -1 . So, Br undergoes reduction.

Hence all the above reactions are redox reactions.

A voting machine is a machine used to register and tabulate votes.

In the given options, It was invented in 1898 is the false statement as it was actually invented in 1875 with some faults in it.

The primary agent of contact metamorphism is heat or temperature.

Activation energy is a minimum amount of energy that required for the chemical reaction to happen or to take place.

The three steps within the aerobic respiration process are glycolysis, the citric acid cycle, and oxidative phosphorylation.

Photosynthesis builds glucose, and what was built in photosynthesis is broken down during aerobic respiration.

Hence, production of ATP from the breakdown of glucose is the main result of aerobic respiration.