Correct Answer : 30th November
The Day of Remembrance for all Victims of Chemical Warfare by the United Nations is observed on 30 November. The day is marked to pay tribute to the victims of chemical warfare. The day also highlights the pledge taken by the Organisation for the Prohibition of Chemical Weapons (OPCW) to eliminate the threat of chemical weapons. Chemical weapons were produced and used on a large scale during World War I, resulting in people dying in thousands. The usage of these lethal weapons was completely curbed in World War II.
History : The Chemical Weapons Convention was adopted in 1993. However, the convention came into force on 29 April, 1997. As per the official website of the United Nations, "the Chemical Weapons Convention is determined to completely exclude the possibility of the use of these lethal weapons for the sake of mankind and to maintain world peace."
At the 20th session of the convention, the Conference of the States Parties to the Chemical Weapons declared that November 30 will be observed as a Memorial Day for the victims of chemical warfare. Finally, the first 'Day of Remembrance for all Victims of Chemical Warfare' was observed in 2005.
As per the Forbes, The Chemical Weapons Convention, which is signed by 189 countries, prohibits the use, production and storing and transfer of chemical weapons on a large scale. It allows the production of chemical weapons (in a very limited quantity) for research purposes only.