Answer:
Rb
Alkali Metals are Group 1 so
Rb it isnt Hydrogen because it is a gas
Explanation:
1. Subscript is below
2. Coefficient large 2 indicates the number of moles
3. Atoms
1/2 O2 + H2 —> H2O
It’s the atoms that balance on each side
Notes that 1/2 is the coefficient and 2 is the subscript in H2 and H2O
Answer:
The number of moles of O atom in 
mol of 
= 1.6
Explanation:
1 molecule of contains 2 atoms of O
So, 
molecules of contains 
atoms of O.
We know that 1 mol of an atom/molecule/ion represents 
numbers of atoms/molecules/ions respectively.
So, molecules of is equal to 1 mol of .
atoms of O is equal to 2 moles of O atom.
Hence, 1 mol of contains 2 moles of O atom.
Therefore, mol of contains 
moles of O atom or 1.6 moles of O atom.
True some explanations are not always based on empirical evidence
If the sealed glass is permeable to sunlight or to transfer of heat will be an open system, but if the sealed glass is a thermic glass and doesn't allow exchange of heat and exchange of solar energy (for example a mirrored glass that reflect the sunlight) and the terrarium is not exchanging energy with the surroundings will be a closed system. It is a question that doesn't specify too many details about the system in the study. It is hard to give a final answer without making some assumptions.
