Which one of the following is not a true solution ?

Options

A. Amalgam
B. Ornamental gold
C. Salt water
D. Milk

Answer

To determine which of the following is not a true solution, we first need to understand what constitutes a true solution. A true solution has the following characteristics:

1. The particles of the solute are less than 1 nanometer (nm) in size.
2. The particles of a true solution are invisible to the naked eye.

Now, let's analyze the options provided:

1. **Amalgam**: This is a homogeneous mixture of a metal and mercury. Since the particles are less than 1 nm and are not visible, amalgam qualifies as a true solution.

2. **Ornamental Gold**: This refers to gold in a colloidal form, where the particles are also at the atomic level and thus not visible. Therefore, ornamental gold is also a true solution.

3. **Salt Water**: Salt water consists of sodium ions (Na+), chloride ions (Cl-), and water molecules (H2O). The size of these particles is also less than 1 nm and they are not visible. Hence, salt water is a true solution.

4. **Milk**: Milk is a colloidal solution. The size of the particles in milk ranges from 1 nm to 1000 nm, which means they are larger than the particles in a true solution. Therefore, milk does not qualify as a true solution.

Based on this analysis, the answer is:

**Milk is not a true solution.**