For air masses to form fronts, they must collide with each other. B.
<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).

=![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>
Every slice of the bread, contains a number of blister like pores. These blister like pores suggests that the air or some gas might be present there. In case, the bread has no air, the surface of the bread must be smooth rather than rough.
The bread is formed by the fermentation of the sugar molecules present in the dough with the help of yeast. These blisters like structure on the bread is present due to the gas produced during fermentation.
Yes. No cancer and heart disease would save millions of lives.