The astronomical unit or also know as AU. Scientists use this because it’s convenient and easier to understand! Hope this helps ;)
Answer: 72 grams of 
are needed to completely burn 19.7 g 
Explanation:
According to avogadro's law, 1 mole of every substance weighs equal to molecular mass and contains avogadro's number 
of particles.
To calculate the number of moles, we use the equation:
Putting in the values we get:
According to stoichiometry:
1 mole of 
requires 5 moles of oxygen
0.45 moles of require= 
moles of oxygen
Mass of 
72 grams of are needed to completely burn 19.7 g
Answer:224
Explanation:
We should answer it with Stoichiometry
We say: 20 g H2× (1 mol/ 2g)× ( 22.4 lit/ 1 mol) = 224
Means: we have 20 grams and every 2g H2, equals to 1 mol of it and every 1 mol of H2, equals to 22.4 lit( because of STP)
hope you got this:)
Any compound with multiple covalent bonds
