<u>Answer:</u>
<em>
heat is released by the combustion of 
of methane</em>
<u>Explanation:</u>
The value of enthalpy determines whether the reaction is exothermic or endothermic. If the enthalpy change is positive, then the reaction is endothermic (heat or energy released) and if the enthalpy change is negative then the reaction is exothermic (heat or energy absorbed).
![\Delta H \ reaction=[ 2(\Delta HfCO_2)+ 4(\Delta HfH_2O)]-[2(\Delta HfCH_4)+4(\Delta HfO_2)]](https://tex.z-dn.net/?f=%5CDelta%20H%20%5C%20reaction%3D%5B%202%28%5CDelta%20HfCO_2%29%2B%204%28%5CDelta%20HfH_2O%29%5D-%5B2%28%5CDelta%20HfCH_4%29%2B4%28%5CDelta%20HfO_2%29%5D)
=![2 ( -(393.5 KJ)/mol)-[2( -74.6 KJ/mol)+4(-241.82 KJ/mol)]](https://tex.z-dn.net/?f=2%20%28%20-%28393.5%20KJ%29%2Fmol%29-%5B2%28%20-74.6%20KJ%2Fmol%29%2B4%28-241.82%20KJ%2Fmol%29%5D)
![= -787 KJ/mol-[ -149.2 KJ/mol-967.28 KJ/mol]](https://tex.z-dn.net/?f=%3D%20-787%20KJ%2Fmol-%5B%20-149.2%20KJ%2Fmol-967.28%20KJ%2Fmol%5D)
<em>In this question, </em><em>the enthalpy of formation</em><em> has positive value and hence the </em><em>reaction is endothermic</em><em> in which the heat is released.
</em>
Answer:
The correct answer is - 1990.
Explanation:
From the graph and year - population size table it is clearly understood that the population of grizzly bear is reduced by 39 number from year 1988 to 1989.
But after 1989 from 1990 onwards population of grizzly bear is consistently rising.
Now, let us analyse the data given in question number 2 .
No. of grizzly bear deaths in Alberta from 1976 to 1988 = 581
No. of grizzly bear deaths in Alberta from 1988 to 2000 = 281
From the above data we can clearly say now that the grizzly bear population deaths starts increasing from 1990.
So, the prediction made in question no. 1 that " the government of Alberta introduced the hunting lottery award in 1990 because in 1989 it decreases and then it starts to go up again in 1990",
Populations
communities
ecosystem
biosphere
