A scientist studied a population of birds for 10 years. During that time, the population was never fewer than 30 birds and never more than 50. Her data showed that over half of the birds born did not survive to reproduce, because of competition for food and predation. She noticed that In a single generation, about 90% of the birds that were born lived to reproduce, and the population increased to 90. Which inference(s) about this population might be true

A particular population limiting factor or factors must have been removed

Explanation:

The population of the birds must have been kept between 30 and 50 individuals by population limiting factors such as the presence of predators within the community or competition for resources such as food or spaces.

For the population to shoot up to 90 all of a sudden, it may be that one or more of the population limiting factors has been removed from the population. It could be that a major predator has been removed from the community or the competition for food/space is now significantly reduced due to more food/space in the community.

this is a good question! i'll do some research and come back when i have the answer!

before, trains worked using the steam engine. thus, it uses heat so it is crucial to apply heat balance. the steam engine absorbs energy during the stage of boiling water. so, this is the endothermic reaction. when the steam is used to work the piston, it has to release this energy through running the train. the excess energy is released as an exhaust to the chimney. this is the exothermic process because it releases energy to the surroundings.