Which one of the following is a group consisting of elements only ?

The correct answer/option is Tin, Lithium, Sodium.

To determine which group consists of elements only, let us analyze the nature of the materials listed in each option by understanding the difference between elements, compounds, and mixtures (alloys):

1. Element: A pure substance consisting of only one type of atom that cannot be broken down into simpler substances by chemical means (e.g., Sodium, Tin, Lithium, Copper, Iron, Aluminium, Potassium).

2. Alloy (Mixture): A metallic substance composed of two or more elements mixed together, usually to enhance properties like strength or corrosion resistance (e.g., Steel, Brass, Bronze).

Let us evaluate each option step-by-step:

• Steel, Iron, Zinc: Iron (Fe) and Zinc (Zn) are chemical elements. However, Steel is an alloy composed mainly of iron and carbon. Thus, this group contains an alloy.

• Sodium, Brass, Potassium: Sodium (Na) and Potassium (K) are elements (alkali metals). However, Brass is an alloy composed of copper and zinc. Thus, this group contains an alloy.

• Bronze, Copper, Aluminium: Copper (Cu) and Aluminium (Al) are elements. However, Bronze is an alloy composed primarily of copper and tin. Thus, this group contains an alloy.

• Tin, Lithium, Sodium:
- Tin (Sn): A chemical element with atomic number 50.
- Lithium (Li): A chemical element with atomic number 3.
- Sodium (Na): A chemical element with atomic number 11.
All three materials in this group are pure chemical elements listed on the periodic table.

Therefore, the group consisting of elements only is Tin, Lithium, Sodium.