The city in Jilin Province with the most difficult high school entrance exam questions is Changchun. This city is known for its rigorous academic standards and competitive atmosphere, which is reflected in the challenging nature of its high school entrance exams. According to data from the Jilin Provincial Education Department, Changchun's high school entrance exam has consistently ranked among the most difficult in the province over the past decade. The exam typically includes a wide range of questions that test students' knowledge across various subjects, requiring not only a strong grasp of the curriculum but also critical thinking and problem-solving skills.

The difficulty of the high school entrance exam in Changchun can be attributed to several factors. Firstly, the city has a long-standing reputation for academic excellence, which has led to a high level of competition among students. Parents and educators in Changchun often emphasize the importance of education, pushing students to excel in their studies from an early age. This competitive environment necessitates a challenging exam that can effectively differentiate between top-performing students and those who may not meet the rigorous academic standards of the city's high schools.

Secondly, the exam content is designed to be comprehensive, covering a wide array of topics within each subject. This ensures that students are well-rounded and prepared for the demands of high school education. The inclusion of complex questions and problem-solving tasks requires students to not only memorize information but also apply their knowledge in practical scenarios, which is a hallmark of the exam's difficulty.

Additionally, the selection process for high schools in Changchun is highly competitive. Only a limited number of seats are available in the city's most prestigious schools, and the entrance exam is the primary criterion for admission. This further intensifies the competition and the difficulty of the exam, as students are vying for a limited number of spots in these elite institutions.

In conclusion, Changchun, Jilin Province, stands out as the city with the most difficult high school entrance exam questions. This is due to the city's competitive academic environment, comprehensive exam content, and the high stakes associated with securing a spot in one of its prestigious high schools. The exam's difficulty serves as a testament to the rigorous academic standards and the commitment to excellence that characterize education in Changchun.