Astudent listed the characteristics of chemical and nuclear reactions.

chemical and nuclear reactions
a --> total mass remains unchanged
b --> small change in mass takes place

which of these statements best explains the identity of reaction a?

a. it is a nuclear reaction because the total mass remains the same when there is a change in the number of protons and neutrons.

b. it is a chemical reaction because the total mass remains the same when the nuclei of the atoms reacting split.

c. it is a nuclear reaction because the total mass remains the same when there is a change in the overall energy of the system.

d. it is a chemical reaction because the total mass remains the same when new substances are formed.

D. It is a chemical reaction because the total mass remains the same when new substances are formed.

Explanation:

A chemical reaction is represented by a chemical equation which show the reactant and products. Reactants are written on left side of arrow while products are written on right side. The number of atoms are remain same however arrangement of atoms is different on both side.

For example:

6H₂O + 6CO₂ + energy  →   C₆H₁₂O₆ + 6O₂

it is known from balanced chemical equation that 6 moles of carbon dioxide react with the six moles of water and created one mole of glucose and six mole of oxygen. The number of atoms are same on both side however arrangement of atoms is different.

While in case of nuclear reaction small change in mass take place.