Secretary of state john hay sent his open door
notes (1899–1900) to world powers to
(1) keep chinese workers from coming to
america
(2) secure a fair settlement in the russojapanese
war
(3) protect united states trading interests in
china
(4) bring a peaceful end to the boxer rebellion

Secretary of State John Hay sent his Open Door Notes (1899-1900) to world powers to protect United States trading interests in China. The correct option among all the options that are given in the question is option "3". These notes were mainly in regards to providing equal opportunity for trades in China and also respecting China's sovereignty, territorial integrity and administration. The principles of operating in China was the same for the British as well as for the United States, but John Hay was the first person to give it a written form. After this the official policy of the United States was based on the written document during the first half of the 20th century.

Cr(oh)3 -> cr(3+) + 3oh-