Is 1 kg of water equal to 1 liter of water?

The density of water is approximately $1 \text{ kg/L}$ (kilogram per liter) at standard conditions (specifically, at $4^\circ \text{C}$). This means that $1 \text{ liter}$ of water has a mass of $1 \text{ kilogram}$.

We are comparing:

• $1 \text{ kg}$ of water (a measure of mass)
• $1 \text{ liter}$ of water (a measure of volume)

Using the density of water:
The mass of $1 \text{ liter}$ of water is given by:

So, $1 \text{ liter}$ of water has a mass of $1 \text{ kg}$.

Since $1 \text{ kg}$ of water has a mass of $1 \text{ kg}$, and $1 \text{ liter}$ of water also has a mass of $1 \text{ kg}$, both quantities are equal.

The correct option is c) Both are equal.