1. which of the following chemical reactions is an oxidation-reduction reaction?
answer
wo3 + 3h2 w + 3h2o
kno3 + licl lino3 + kcl
caso4 + 2nacl na2so4 + cacl2
mg(no3)2 + 2hbr mgbr2 + 2hno3

2. according to the collision theory and model created to explain the collision theory, what is the best explanation for why a higher concentration makes a reaction go faster?
there are more collisions per minute.
it increases the distance between the particles.
it increases the average kinetic energy of the particles.
it increases the average kinetic energy and there are more collision per minute

Explanation:

1.  When there is loss of electrons or increase in oxidation state of an element in a chemical reaction then it is known as oxidation.

Whereas when there is gain of electrons or decrease in oxidation state of an element in a chemical reaction then it is known as reduction.

For example,

Oxidation half-reaction:

Reduction half-reaction:

Therefore, out of the given options chemical reaction is an oxidation-reduction reaction.

Whereas in other given reactions, there is no change in oxidation state of atoms. Hence, they are not oxidation-reduction reactions.

2.   According to collision theory, more is the number of collisions occurring in a chemical reaction more faster will be the rate of reaction.

Therefore, higher is the concentration that is, more will be the number of reactants present in the chemical reaction. Therefore, more will be the number of collisions.

Hence, we can conclude that there are more collisions per minute.

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.