Chemistry Questions

Electronegativity, is a chemical property that describes the tendency of an atom to attract a shared pair of electrons (or electron density) towards itself.

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

An ionic bond is a chemical bond between two atoms in which one atom seems to donate its electron to another atom.

Here in the given compounds, the compound that contains ionic bond is CaO, Calcium oxide.

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.

S8 is an elemental form of sufur. In elemental form it can't be reduced or oxidized. Hence, it oxidation number is zero and thus sulfur is zerovalent here.

Compounds are substances is true about them.

Yes, Carbon disulfide is prepared by heating sulfur and charcoal. 

S2 + C ----> CS2

The relationship between a cathode and an anode involves the transfer of electric charge between them. The cathode is the negative terminal on the battery, which has zero electric potential. The anode is the positive terminal on the battery and has the battery's maximum electric potential. Current flows from the battery's anode (positive terminal) to the cathode (negative terminal). In electron flow, electrons leave the negative side of the battery and move towards the positive side of the battery.

Hence, The relationship between a cathode and an anode involves Electrons.