The answer to your question is :64 cm cubed
1.it is readily available since hydrogen is a basic earth element and it's very abundant.
2. It doesn't produce harmful emissions.
Disadvantages
1.it is expensive. It is expensive because it takes a lot of time to separate the element from others.
2.it is difficult to store. Even moving a tiny bit of hydrogen would be very expensive.
3. It is highly flammable. Since it is a very powerful source of fuel, hydrogen can be very flammable.
Convection is when heat and cold air go around in a circle connecting the source of air, radiation is like the suns heat beam, conduction is the transfer of any source by touching and idk what biosphere and geosphere is sorry..
