The general idea is that after hearing the loud sound, the child began to pay attention to every sound that he or she could hear. When we are "alert", we have this kind of fixed attention. When we use "alert" as a noun, we are describing something that is supposed to "grab" attention. For example, a "tornado alert" is a kind of warning that is meant to make us aware that the danger of a tornado is very nearby.

If nothing else, Reginald must be a loyal friend. In this sense, it is fair to say that he is faithful. Whenever we are faithful to someone or something, we never abandon it. A faithful husband never falls in love with another woman. A faithful friend always helps those whom he or she loves. A faithful worker will stay with an employer for years.

Since the sentence begins with "although", we know that it will express a contrast. It contrasts Richard's concern with the actual reality of the mistake in question. If he is very worried about the mistake, this would seem to indicate that it is a major or large mistake. In contrast to this, it must have been a rather small mistake. Now, the best word to describe such a small or unimportant mistake is "minor." This word can be used to describe anything that is small or undeveloped. Hence, we call a young person a "minor" because he or she has not yet "grown up." That is, he or she has not fully matured. 

If we wanted to speak in a very straightforward manner, we could say that the idea proposed was not "doable." This is the basic idea of the second sentence. The word "practical" is used in several different ways. Sometimes, we contrast practical things to theoretical ones. Some people are always thinking of ideas that are too abstract, idealistic, or impossible to be accomplished. Such people are impractical. Whenever we say that someone is "practically minded," we mean that he or she likes to accomplish things—to "get things done." Whenever a task is not practical, it is not "doable." This is the case with the idea mentioned in the first sentence in this question.

The most tempting wrong answer for this question is likely "sickly," but that doesn't make much sense regarding someone's ability to move a chair. Instead, the idea is that Thomas made weak attempt to move the chair, meaning that it was a feeble attempt. The adverb "feebly" describes an action that is physically weak, often due to illness or being old. (It can also be used metaphorically, as when we say that a lamp gives off "feeble light.")

The second sentence describes Patricia as being a person who is able to suffer with other people. When we can show sympathy in this way, we are "compassionate." Interestingly both "sympathy" and "compassionate" come from similar roots, but from different languages! "Sympathy" comes from Greek roots meaning suffering with. "Compassionate" comes from Latin roots meaning the same thing!

The contrast in this sentence is between Jessica's unique response to math class and what seems to be the normal response—anxiety. When something is "typical" it is ordinary or normal. We can say, for example: "That was his typical greeting; he always said, 'Hey you,' when he ran into someone."

The young man apparently did not think he could ever die. This means that he doubted his mortality. The words "mortal" and "mortality," as well as "morgue" and "morbid" all come from roots having to do with death. The adjective "mortal" means able to die. Thus, the word "immortal" means not able to die. (Remember that the "i-" prefix can mean "not".) The man seems to have realized that he is actually not immortal.

It seems that Rachel's words were very hurtful. Therefore, you should choose a word that most closely describes such hurtful action. When we abuse someone, we hurt them—either physically or at least emotionally. In this sentence, the abuse in question is verbal and emotional. Thus, the adjective "abusive" is the best option.

This sentence does not really indicate much about Henry's attitude. We do not know if he is frightened or angered by his brother's upcoming slap. All that we know is that he is waiting for it to happen. When we think that something is about to happen and then wait for it, we are said to "anticipate" that thing. That is what Henry is being described as doing in this sentence.