Question

The density of air at room temperature is about 1.2 g/L. This is the same as

Answer 1

The correct answer is
C) 1200 g/m3. 

Let's see why. The relationship between liters and cube decimeters is
$1 L = 1 dm^3$
Therefore, 
$1 g/L= 1 g/dm^3$
However, we also know that
$1 dm^3 = 10^{-3} m^3$
Therefore, 
$1 L = 10^{-3} m^3$
and 
$1 \frac{g}{L}= 1 \frac{g}{10^{-3} m^3} =1 \cdot 10^3 \frac{g}{m^3} =1000 \frac{g}{m^3}$

Therefore, the density of the problem $1.2 g/L$ becomes
$d=1.2 g/L=1200 g/m^3$