The density of iron is `7.8xx 10^3 "kg m"^(-3)` What is its relative density?

Explanation

To find the relative density of iron, we can follow these steps:

### Step 1: Understand the concept of relative density
Relative density (also known as specific gravity) is defined as the ratio of the density of a substance to the density of water. It is a dimensionless quantity.

### Step 2: Identify the density of iron
The density of iron is given as:
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