There are no errors in this sentence. The sentence joins two independent clauses without the use of a coordinate conjunction, so there should be a semicolon before the word "she." Furthermore, a comma is inappropriate in this place because you would need a conjunction in addition to the comma, which is absent here. A colon is also incorrect here because the second clause does not explain anything in or about the first clause, but adds more information about something not previously mentioned. The other sentences contain errors in verb-noun agreement (e.g. "Her hobby were collecting...") and tense shifts (e.g. "Her hobby were collecting...she even sets..."). The correct answer choice is: "Her hobby was collecting models of various types of vehicles; she even set aside a room just for the models."

The above sentence is correct. The sentence joins two independent clauses together with the use of the coordinate conjunction "but," so there should be comma before this word. Furthermore, the word "whether" is appropriate; it is not necessary to use the common phrases "whether or not" or "whether...or," and, in fact, "whether...or" would be completely out of place here because there is no additional option after the "whether." The correct choice is: "Chelsea wanted to visit her family over the weekend, but she was unsure whether she would be able to finish her work if she did."

Note: In the choice that omits "she" after the word "but," the comma cannot be used because this omission makes the last clause a dependent one, since it lacks a subject. While it is obvious that the "she" is implied, grammatically, the "she" needs to literally be in the sentence in order for it to function as an independent clause.

This sentence contains no errors. The phrase "From time to time" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "From time to time, Juan liked to look at his trophies."

This sentence contains no errors. The word "because" does not take a comma before it, even though it joins two independent clauses. "Its" is the correct possessive form of the word "it," and "their" would not be appropriate because it describes "company," which is singular. The usage of "it" instead of reiterating "the company" is also not vague because there is only one singular noun (the company) to which it could possibly refer. The correct answer is, "The company's new acquisition surprised everyone because they were not able to see how it would help to its core business."

This sentence contains no errors. It joins two independent clauses with the use of the coordinate conjunction "yet," which properly has a comma preceding it. The correct choice is, "She had many hobbies, yet she rarely had the time to do them."

This sentence contains no errors. It joins two independent sentences without the use of a coordinate conjunction, so a semicolon should be present after "horizon." Furthermore, the phrase "especially with the invents of Google's car and various competitions" is an example of an introductory phrase, explaining information necessary to the context of the sentence, but outside of the main sentence, grammatically. These types of phrases must be followed by a comma in order to separate them from the rest of the sentence. The correct answer choice is, "It seems like the age of driverless cars are on the horizon; especially with the advent of Google's car and various competitions, the average person may be able to afford one within the next few decades."

This sentence does not contain any errors. This sentence combines two independent clauses without the use of a coordinate conjunction, so there should be a semicolon before the word "it." No colon is needed after "than." The correct choice is, "Russia is well known for its natural gas resources; it produces more than 10% of all the world's gas."

This sentence contains no errors. The phrase "such as Elon Musk" is functioning as a parenthetical expression to give an example of one of the people working to the end of "consumer space travel," so it should be surrounded by commas. While this phrase could also function as a normal part of the main clause (thus, eliminating the need for commas), that is not an option available in the choices. The correct answer is, "People, such as Elon Musk, are working in order to make consumer space travel a reality."

There are no errors in the above sentence. This sentence joins two related independent clauses without the use of a coordinate conjunction, so there should be a semicolon present after the word "time." In the other sentences, there are issues with parallelism (found...finds), verb agreement (loved to plays), word errors (freetime is not one word), or using a comma where a semicolon should be used. The correct choice is, "Christopher loved to play video games in his free time; he found playing them relaxing."

There are no errors in this sentence. There is no need for additional punctuation. The word "because" is appropriate because it acts to join the two clauses and show a cause and effect. The words "but" and "and" do not do this and are therefore inappropriate. The correct answer is, "Naomi was learning to play the guitar because she liked the sound of the instrument."