Answer:
150 million kilometres
Explanation:
The astronomical unit (symbol: au, or AU or AU) is a unit of length, roughly the distance from Earth to the Sun and equal to 150 million kilometres (93 million miles) or 8.3 light minutes.
To solve the exercise it is necessary to keep in mind the concepts about the ideal gas equation and the volume in the cube.
However, for this case the Boyle equation will not be used, but the one that corresponds to the Boltzmann equation for ideal gas, in this way it is understood that

Where,
N = Number of molecules
k = Boltzmann constant
V = Volume
T = Temperature
P = Pressure
Our values are given as,




Rearrange the equation to find V we have,



We know that length of a cube is given by

Therefore the Length would be given as,



Therefore each length of the cube is 3.44nm