Answer:
Most stars are rather simple things. They come in a variety of sizes and temperatures, but the great majority can be characterized by just two parameters: their mass and their age. (Chemical composition also has some effect, but not enough to change the overall picture of what we will be discussing here. All stars are about three-quarters hydrogen and one-quarter helium when they are born.)
Answer:
I would say A
Explanation:
our ancestors are the people that lived long before us
Answer:
= -356KJ
<em>therefore, the reaction where heat is released is exothermic reaction since theΔH is negative</em>
Explanation:
given that enthalpy of gaseous reactants decreases by 162KJ and workdone is -194KJ
then,
change in enthalpy (ΔH) = -162( released energy)
work(w) = -194KJ
change in enthalpy is said to be negative if the heat is evolved during the reaction while heat change(ΔH) is said to be positive if the heat required for the reaction occurs.
At constant pressure the change in enthalpy is given as
ΔH = ΔU + PΔV
ΔU = change in energy
ΔV = change in volume
P = pressure
w = -pΔV
therefore,
ΔH = ΔU -W
to evaluate energy change we have,
ΔU =ΔH + W
ΔU = -162+ (-194KJ)
= -356KJ
<em>therefore, the reaction where heat is released is exothermic reaction since theΔH is negative</em>
