Why are wires given slack in summer and not in winter?

This is because of the thermal expansion and contraction of the wires. Most materials expand when they are heated and contract when they are cooled. The amount of expansion or contraction is a function of the material's properties (specifically the coefficient of thermal expansion), the amount of heat supplied, etc. This means that some materials may expand (or contract) more as compared to others, for the same amount of heat supplied. 

In summers, due to temperature increase, the wires expand. In comparison, the temperature decrease during winter will cause the wires to contract. If no slack was available during the summer and the wires were connected very tightly between any two sections, there would be no room for contraction in the winter season and the wires would break. To avoid that scenario, some slack is left in the wire to provide room for contraction.

Hope this helps.

112g of iron reacted completely with 64g of sulfur. What mass of iron sulfide was made?

There are two common sulfides of iron:

Iron(II)sulfide is FeS

Iron(III)sulfide is Fe2S3

Since we're told that 112 grams of iron reacts completely with 64 grams of sulfur, we can determine which compound formed by the mole ratio of Fe to S. Find the number of moles of each reactant using their molar mases:

112 g Fe x 1mol/55.8 g = 2.01 moles

64 g S x 1 mol/32.1 g = 1.99 moles S

Since the mole ratio is about 1:1, the formula is FeS and the equation is:

`Fe + S -> FeS`

According to the law of consevation of mass, the mass of the product(s) equals the mass of reactant(s) so the mass of FeS that formed is:

112 g + 64 g = 176 g

This method works because there's only one product and we know that both reactants reacted completely. If there's more than one product or there's an excess of one reactant, you could use dimensional analysis to convert from grams of the limiting reactant to moles, then to moles of the product in question, then to grams of the product. 

How did the Great Depression in America affect the economies of Europe?

The Great Depression was a global event, and many historians (and some observers at the time) located many of its origins in Europe. It is not as simple as saying that the Depression began in the United States and spread to Europe. But certainly the collapse of the American financial system reverberated in the economies of Europe. After World War I, the major European nations had received billions of dollars in loans from American banks and the US Treasury, both of whom were reluctant to write off these obligations even when it became apparent that they were hindering Europe's economic growth. Basically, the Great Depression was brought on by a collapse of the international banking system. Bank failures in the United States led to bank failures in Europe, because they were dependent, some more directly than others, on American capital. But at the same time, European bank failures led to similar problems for American financial institutions because they held so many European assets. So the effects of the Great Depression were similar in European nations as in the United States. What differed from nation to nation, both within Europe and elsewhere, were the responses of individual governments. 

Put these words in order to show how oxygen gets into your blood: mouth, trachea, alveoli, bronchi.

The trachea is a tube which passes between the mouth and the lungs (this is also sometimes referred to as the windpipe). This is a separate tube entirely from the esophagus. The function of the trachea is to allow the passage of air while the esophagus allows the passage of food and drink from the mouth to the stomach. 

When the trachea reaches the lungs, the passageway branches into several smaller tubes which also allow the passage of air. These smaller tubes are called the bronchi. (Note that the word bronchi is plural, bronchus is singular).

Alveoli are small sacs within the lungs where gas exchange between the air and the blood actually occurs. Alveoli are attached to the bronchi.

Thus, air passes from the mouth, to the trachea, to the bronchi,, and finally to the alveoli. 

"The Most Dangerous Game" portrays good and evil using the two main characters: Rainsford and General Zaroff. Which one of them is good and...

What a good question.  Generally speaking, general Zaroff is evil.  The extent of his evil is seen in his brazen desire to hunt humans for his own pleasure, or to put it another way to hunt humans to get over his boredom.  Here is what the text says:

To Rainsford's questioning glance the general said, "Ennui. Boredom."

From this perspective, Zaroff is the epitome of evil in this story. When it comes to Rainsford, we might think that he is the opposite of Zaroff, but he is not. He is not completely good. In the beginning of the story, Rainsford comes off as a arrogant hunter.  When his friend, Whitney, said that animals might have feelings, Rainsford dismissed it without hesitation.  He says:

"Bah! They've no understanding."

"Even so, I rather think they understand one thing--fear. The fear of pain and the fear of death."

At the end of the story, Rainsford becomes a hunter again.  He kills Zaroff.  Some might say that he had to do so, but this is not clear.  

In conclusion, no one comes off as good.  Zaroff is evil. Rainsford is better than Zaroff, but not good.  This is a story where no one is good.

How can you avoid plagiarism?

The best and easiest way to avoid plagiarism is to make sure that your work is entirely original.  

Of course that is really hard to do, if your teacher has asked you to write a research paper.  If that is the case, you need to give credit where credit is due.  If you are using the exact words from another author or source, then it needs to be in quotes.  That quotation needs to then be cited in proper format.  Even if you are paraphrasing somebody else's ideas or words, you must give that person credit by alerting your reader with a citation.  Any in text citations that occur also need to be fully cited in a "works cited" or bibliography page.  I always tell my students that if they are in doubt about whether or not they should cite something, they should cite it to be safe.  

Depending on the subject content, you might have to cite in APA or MLA format.  MLA is generally used in literature, while APA is generally used in history and the sciences.  Making a works cited page has become a lot less tedious than it used to be, because there are a number of good online generators.  I'll link a couple below.  

Why does Holden watch the game from the hill in The Catcher in the Rye?

When the novel opens, Holden is standing on top of a hill looking down at the football players and the fans. He gives two reasons why he is on the hill rather than down at the game, but neither reason is entirely satisfactory. The first reason is that he has been "ostracized" by the fencing team for losing all their equipment in New York. Holden is, or was, the manager of the team and responsible for the foils, masks, and other fencing equipment. This hardly explains why he has gone up to the top of Thomsen Hill, though. More likely, Holden feels ashamed of himself and wants to be alone. If he were to join the crowd watching the game, word would get around that he had returned early because the fencing match had to be called off and that he was responsible. Holden's descriptions of his last days at Pencey reveal that he is an outsider and a loner even without being "ostracized." He doesn't appear to have a single friend at the school. This is partly because he is known to be flunking practically all his courses. Many of the students must already know that Holden has been expelled. 

Holden says that his other reason for being up on Thomsen Hill, or at least not at the game, is that he is on his way to visit his history teacher Mr. Spencer, who is confined to his bedroom with the grippe. This hardly seems to explain why Holden would have climbed a hill to get to Mr. Spencer's home. Holden's real reason becomes apparent when he says,

Only, I wasn't watching the game too much. What I was really hanging around for, I was trying to feel some kind of a good-by. . . I mean I've left schools and places I didn't even know I was leaving them. I hate that. I don't care if it's a sad good-by or a bad good-by, but when I leave a place I like to know I'm leaving it. If you don't, you feel even worse.

Holden has already flunked out of two other prep schools. He obviously feels miserable. He will have to face his parents and be made to feel even more miserable for disappointing them. It is difficult to understand this boy because he doesn't even understand himself. It is easy to commiserate with his feelings, though. He has nobody to say good-bye to because everybody dislikes him, with the possible exception of old Mr. Spencer, who sent him a note asking him to come and see him before he leaves for his home in New York City. That meeting takes place in Chapter Two, and it doesn't make Holden feel any better. It turns into a lecture from an old man in a room that smells of Vicks Nose Drops. By the time Holden gets through describing a few of his other acquaintances at Pencey, it isn't hard to understand why he makes the sudden rash decision to stop just "hanging around" and leave for New York immediately.