<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:
Because natural selection selects for it. Thus it persists.
Explanation:
You have to understand heterozygote advantage. Basically, it's where heterozygotes have an advantage over homozygotes. In the case of sickle cell disease, heterozygotes have an advantage, and natural selection favors whatever is advantageous. Thus, because heterozygotes each have one recessive sickle-cell allele, as natural selection favors the heterozygotes, the recessive sickle-cell allele persists and remains in the gene pool.
Nitrogenous base DNA consists of four unique nucleotides that each contain one unique nitrogenous base—adenine (A), thymine (T), cytosine (C), or guanine (G).
The specific arrangement of these four bases within the DNA of each organism gives that organism its unique traits; here are the arrangements:
-<u>Adenine</u> is paired with <u>Thymine</u> (think of A for apple and T for tree)
-<u>Cytosine</u> is paired with <u>Guanine</u> (think of C for car and G for garage)
search "DNA base pairs" and go to images for better understanding
The groundwater is being discharged faster than it is being recharged is the data suggested.
Option D
<h3><u>Ex
planation:</u></h3>
Ground water level is the level of underground storage of water above the impermeable rock layer. The underground water is getting filtered through different layers of permeable rocks before it enters the final layer. So it’s fresh and ready to be consumed as it is taken out. Thus for centuries, it’s being used as the source of drinking water.
But with increasing population, the ground water is being consumed at the rate very faster than it can be refilled from different sources like precipitation, rivers and other water bodies. So its level tends to get lower and lower as this continues until the point it gets finished.
