B. Covalent (Bond) I hope this helps! ^^
<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:
Until recently, most neuroscientists thought we were born with all the neurons we were ever going to have. As children we might produce some new neurons to help build the pathways - called neural circuits - that act as information highways between different areas of the brain. But scientists believed that once a neural circuit was in place, adding any new neurons would disrupt the flow of information and disable the brain’s communication system.
In 1962, scientist Joseph Altman challenged this belief when he saw evidence of neurogenesis (the birth of neurons) in a region of the adult rat brain called the hippocampus. He later reported that newborn neurons migrated from their birthplace in the hippocampus to other parts of the brain. In 1979, another scientist, Michael Kaplan, confirmed Altman’s findings in the rat brain, and in 1983 he found neural precursor cells in the forebrain of an adult monkey.
These discoveries about neurogenesis in the adult brain were surprising to other researchers who didn’t think they could be true in humans. But in the early 1980s, a scientist trying to understand how birds learn to sing suggested that neuroscientists look again at neurogenesis in the adult brain and begin to see how it might make sense. In a series of experiments, Fernando Nottebohm and his research team showed that the numbers of neurons in the forebrains of male canaries dramatically increased during the mating season. This was the same time in which the birds had to learn new songs to attract females.
Why did these bird brains add neurons at such a critical time in learning? Nottebohm believed it was because fresh neurons helped store new song patterns within the neural circuits of the forebrain, the area of the brain that controls complex behaviors. These new neurons made learning possible. If birds made new neurons to help them remember and learn, Nottebohm thought the brains of mammals might too.
Other scientists believed these findings could not apply to mammals, but Elizabeth Gould later found evidence of newborn neurons in a distinct area of the brain in monkeys, and Fred Gage and Peter Eriksson showed that the adult human brain produced new neurons in a similar area.
For some neuroscientists, neurogenesis in the adult brain is still an unproven theory. But others think the evidence offers intriguing possibilities about the role of adult-generated neurons in learning and memory.
if wrong report me
-They ignore historical evidence showing how present-day arrangements contrast with earlier social arrangements
- They direct attention away from current social inequalities, insisting that these inequalities are so deeply rooted that attempting to change them would be impossible.
-They ignore variations in social arrangements in other present-day societies, which show that social life may be organized differently
