Answer:
105
Explanation:
Density = mass/volume
therefore volume = mass/density
826/7.9=105 (To three significant figure)
Answer:
The correct option is C
Explanation:
From the question we are told that
The reaction is

Generally
Here
is the change in enthalpy
is the change in the internal energy
is the difference between that number of moles of product and the number of moles of reactant
Looking at the reaction we can discover that the elements that was consumed and the element that was formed is
and
and this are both gases so the change would occur in the number of moles
So
The negative sign in the equation tell us that the enthalpy
would be less than the Internal energy 
The correct response is A. Only the Fe is unbalanced.
Answer:
B.
Explanation:
the SI unit for density is the kilogram per Cubic meter
Explanation:The five major branches of chemistry are organic, inorganic, analytical, physical, and biochemistry.
...
Sub-branches of physical chemistry include:
Photochemistry — the study of the chemical changes caused by light.
Surface chemistry — the study of chemical reactions at surfaces of substances