Este X là hợp chất thơm có công thức phân tử là C₉H₁₀O₂. Cho X tác dụng với dung dịch NaOH, tạo ra hai muối đều có phân tử khối lớn hơn 80. Công thức cấu tạo thu gọn của X là

A. CH₃COOCH₂C₆H₅

B. HCOOC₆H₄C₂H₅

C. C₆H₅COOC₂H₅

D. C₂H₅COOC₆H₅

Đun nóng este CH₃COOC₆H₅ (phenyl axetat) với lượng dư dung dịch NaOH, thu được các sản phẩm hữu cơ là

A. CH₃OH và C₆H₅ONa

B. CH₃COOH và C₆H₅ONa

C. CH₃COONa và C₆H₅ONa

D. CH₃COOH và C₆H₅OH

Read the following passage and mark the letter A, B, C or D on your answer sheet to indicate the correct word or phrase that best fits each of the numbered blanks from 25 to 29. Fill in the appropriate word in question 26

  In Germany, it's important to be serious in a work situation. They don't mix work and play so you shouldn't make jokes (25) ________ you do in the UK and USA when you first meet people. They work in a very organized way and prefer to do one thing at a time. They don't like· interruptions or (26) ________ changes of schedule. Punctuality is very important so you should arrive on time for appointments. At meeting, it's important to follow the agenda and not interrupt (27) ________ speaker. If you give a presentation, you should focus (28) ________ facts and technical information and the quality of your company's products. You should also prepare well, as they may ask a lot of questions. Colleagues normally use the family names, and title - for example 'Doctor' or 'Professor', so you shouldn't use first names (29) ________ a person asks you to.

A. abruptly

B. suddenly

C. sudden

D. promptly

Để phân biệt các kim loại Al, Fe, Zn, Ag, Mg. Người ta dùng thuốc thử nào sau đây

A. dd HCl và dd NaOH

B. dd HNO₃ và dd NaOH

C. dd HCl và dd NH₃

D. dd HNO₃ và dd NH₃

Có thể dùng một hóa chất để phân biệt Fe₂O₃ và Fe₃O₄. Hóa chất này là

A. dd HCl loãng

B. Dd HCl đặc

C. Dd H₂SO₄ loãng

D. Dd HNO₃ loãng

mentioned (D) less details. 

Mark the letter A, B, C or D on your answer sheet to indicate the sentence that best combines each pair of sentences in the following questions.

Our flight was delayed. We decided to spend time at the duty-free shops.

A. As our flight was delayed, we decided to spend time at the duty-free shops. 

B. We have been spending time at the duty-free shops since our flight was delayed.

C. We decided to spend time at the duty-free shops in case our flight was delayed. 

D. Although our flight was delayed, we decided to spend time at the duty-free shops.