Câu 17: Ion dichromate bị khử bởi ion chloride theo: \(14H^+\left(aq\right)+Cr_2O_7^{2-}\left(aq\right)+6Cl^-\left(aq\right)\rightarrow2Cr^{3+}\left(aq\right)+3Cl_2\left(aq\right)+7H_2O\left(l\right)\)

Nếu \(\left[Cl^-\right]\) giảm với tốc độ \(0,37\) \(mol.L^{-1}phút^{-1}\) thì nồng độ của \(Cr^{3+}\left(aq\right)\) thay đổi như thế nào?

A. Tăng \(0,12\) \(mol.L^{-1}phút^{-1}\)

B. Tăng \(1,11\) \(mol.L^{-1}phút^{-1}\)

C. Giảm \(0,12\) \(mol.L^{-1}phút^{-1}\)

D. Giảm \(1,11\) \(mol.L^{-1}phút^{-1}\)

Câu 4: Để xác định hàm lượng của FeCO₃ trong quặng siderite, người ta có thể làm như sau: Cân 0,300 g mẫu quặng, xử lí theo một quy trình thích hợp, thu được dung dịch FeSO₄ trong môi trường H₂SO₄ loãng. Coi như dung dịch không chứa tạp chất tác dụng với KMnO₄. Chuẩn độ dung dịch thu được bằng dung dịch KMnO₄ 0,02 M thì dùng hết 12,5 mL. Tính thành phần % theo khối lượng của FeCO₃ trong quặng.

Mark the letter A, B, C or D to indicate the correct answer to each of the following questions. 

Question 15: Her 5000-metre run paled into ___________ when compared with the marathon her grandfather completed the following week.
A. indifference                 B. insignificance                  C. inferiority                  D. immateriality

Question 16: ____________ raw sewage and all kinds of industrial discharge, so the problem has improved.
A. There has been                                                B. There used to be
C. There seem to be                                             D. There were likely to be

Question 17: With its crumbling facade and weakened structure, the historic building must ____________ over the centuries.  
A. deteriorate                  B. be deteriorating                   C. have deteriorated                   D. be deteriorated

Question 18: Never in recent history ___________ a global crisis ___________ the world with such unprecedented speed and magnitude as the Covid-19 pandemic.

A. has − overtaken                   B. had − overtaken                  C. did − overtake                   D. would − overtake

Question 19: Henry complained in a querulous voice about _____________ .
A. being woken up                                              B. having woken up
C. having been woken up                                  D. getting him woken up

Choose a suitable word or phrase (marked A, B, C, or D) to fill in each blank.

Question 1: Walking in further, she found the bathroom was adjacent __________ the dressing room.
A. with             B. on              C. to               D. in

Question 2: They shot the film in Ireland, ___________ avoiding the problems associated with filming in a hot climate.
A. whereby          B. nearby          C. thereby          D. close by

Question 3: Much of the wealth he accumulated was invested in real estate in numerous rural areas in the ___________ of Carpathian.
A. vicinity            B. territory             C. region             D. enclave

Question 4: The standard of service at that hotel has ____________ since we last stayed there.
A. deteriorated            B. languished            C. degenerated             D. debilitated

Question 5: He was famously a war hero, a connoisseur, a philanthropist and a devoted family man who had to ____________ an appalling succession of tragedies.
A. tackle             B. confront             C. withstand              D. approach

Choose the best option:

Question 1: The concerns of reformers gradually had some impact ____________ the working condition of chil­dren.

A. with                   B. of                  C. upon                  D. about

Question 2: It is no longer a privilege for children to attend school and all children are expected ____________ a significant part of their day in a classroom.

A. to spend                 B. to have spent                   C. spending                 D. being spent

Question 3: Whether childhood is itself a recent invention has been one of ____________ issues in the history of childhood.

A. the more intense debated                                    B. the most intensely debated

C. the less debatably intensive                                 D. the most intensely debatable

Question 4: The reintroduction of flame to the Olympics occurred at the Amsterdam 1928 Games, ___________ a cauldron was lit yet without a torch relay.
A. in which                 B. whose                C. for which                 D. where

Question 5: Humanity ____________ to approximately three billion networked telephones, computers, traffic lights and even fridges and picture frames since these things can facilitate our daily lives.

A. connected                    B. has been connected                    C. has connected                    D. is being connected

4. Tác dụng với dd muối

KL hoạt động mạnh hơn (trừ KLK và KLKT) khử được ion KL yếu hơn trong dd muối thành KL tự do.

VD: Fe + CuSO₄ \(\rightarrow\) ................................................................

       Cu + AgNO₃ → ................................................................

       Ag + CuSO₄ → ................................................................