To solve this exercise it is necessary to apply the concepts related to Robert Boyle's law where:

Where,
P = Pressure
V = Volume
T = Temperature
n = amount of substance
R = Ideal gas constant
We start by calculating the volume of inhaled O_2 for it:


Our values are given as
P = 1atm
T=293K 
Using the equation to find n, we have:




Number of molecules would be found through Avogadro number, then


A spinning top is the answer
As long as the sound is inside the helmet of your space suit, it will travel
at the same speed as it would on Earth, through the same mixture of gases
at the same pressure. Once it passes through the visor of your space helmet,
its 'speed' has no meaning, since there's nothing for sound to travel through on
the moon, and it doesn't travel at all.
In order for the object to move upward, it needs an upward force
that's at least equal to its own weight.
Weight = (mass) x (gravity) = (35 kg) x (9.8 m/s²) = 343 N.
The engine thrust has to be more than 343 N.