Question

Define element.
A) Can be broken down by chemical reactions into simpler substances.
B) Cannot be broken down by chemical reactions into simpler substances.
C) Maybe be broken down by chemical reactions into simpler substances.
D) Both B and C.

Answer 1

Hint: We can classify the matter into elements and compounds. Out of elements and compounds, determine which can be broken down into simpler substances and which cannot be broken down into simpler substances through chemical reactions.

Complete answer:
A compound can be broken down by chemical reactions into simpler substances.
For example, We can break water into constituent elements hydrogen and oxygen by electrolysis. Another example is the thermal decomposition of calcium carbonate to obtain calcium oxide and carbon dioxide. Here, a compound is broken into smaller compounds.
An element is a pure substance and contains only one type of atom. It is homogenous. Copper, silver gold, iron, mercury, sodium, potassium, magnesium, calcium and aluminum are some examples of elements. Thus, sodium metal is an element as it is made from only sodium atoms.
An element cannot be broken down by chemical reactions into simpler substances

Hence, the correct option is the option (B).

Note: We can consider an atom as indivisible. Even though the atom contains subatomic particles such as protons, neutrons and electrons, We cannot break the atom into these subatomic particles through chemical reactions. We need nuclear transformations to break heavy atoms into smaller atoms. But nuclear reactions do not come under normal chemical reactions. Chemical reactions are concerned only with exchange of electrons between different atoms. Nuclei do not participate in chemical reactions.