A Police officer reacts to protestors outside the Piet Retief Magistrates court where the five accused in the shooting of the Coka brothers on the Pampoenkraal farm appeared, Mhkondo, Mpumalanga, South Africa on April 19, 2021. (Photo by Jacques Nelles)

A resident reacts as a health worker collects a swab sample to test for the Covid-19 coronavirus in Colombo on July 27, 2021. (Photo by Ishara S. Kodikara/AFP Photo)

Actress Riley Keough reacts to the cameras at the Baby2Baby 10-Year Gala in Los Angeles, California on November 13, 2021. (Photo by Action Press/Rex Features/Shutterstock)

Miss Alaska Emma Broyles, center, reacts after being crowned Miss America at Mohegan Sun, Thursday, December 16, 2021, in Uncasville, Conn. (Photo by Jessica Hill/AP Photo)

A woman is helped as she reacts on the floor amid anti-government protests after Peru's former President Pedro Castillo was ousted, in Lima, Peru on January 23, 2023. (Photo by Pilar Olivares/Reuters)

Filipino informal settlers react during a demolition raid at a shanty town in Pasay City, Metro Manila, Philippines, 01 August 2024. (Photo by Francis R. Malasig/EPA)

A Palestinian man reacts after his house was flooded by rain water in Khan Younis in the southern Gaza Strip, November 9, 2015. (Photo by Ibraheem Abu Mustafa/Reuters)

These beautiful shots may look like works of modern art – but they are actually close-ups of chemical reactions. The works were snapped with the help of a group of scientists from the University of Science and Technology of China (USTC) in Anhui, China. Here: Zinc reacting with lead nitrate in a soft gel to form lead crystals. (Photo by Yan Liang/Caters News)