Answer: Hydrogen that is not used in balloons because hydrogen burns very easily.
pls mark brainliest
Answer: 4.
and 
Explanation:
a) The given reaction is 
As the mass on both reactant and product side must be equal:


As the atomic number on both reactant and product side must be equal:



b) 
Total mass on reactant side = total mass on product side
15 =15 + x
x = 0
Total atomic number on reactant side = total atomic number on product side
8 = 7 + y
y = 1

Methane composes most of the natural gas.
I believe it is B. Green pods are recessive.