Leap years occur every 4 years on years divisible by 4 (e.g., 2020, 2024, 2028).

Mercury is closest to the Sun and has the fastest average orbital speed (approx. 47.87 km/s).

Standardized admissions tests like the SAT are designed as predictive measures of first-year collegiate academic readiness.

The SAT is a standardized entrance test in the US, originally named Scholastic Aptitude Test and later Scholastic Assessment Test.

The Agni missile is a family of medium to intercontinental range ballistic missiles developed by India, with the first test firing taking place in 1989.

In 2005, China's rapid economic growth was accompanied by challenges related to its large population 1. Resource management, environmental sustainability, and social equity were areas of concern.

The first commitment period of the Kyoto Protocol, an international treaty aimed at reducing greenhouse gas emissions, was scheduled to end on December 31, 2012 [2, p22]. Subsequent discussions and amendments (like the Doha Amendment) extended commitments for some parties, but the initial period concluded in 2012. The Paris Agreement, adopted in 2015, has since become the primary international framework for climate action post-2020.

The United States signed the CTBT in 1996 but has not ratified it. Ratification requires Senate approval, which has not been granted.

The International Day for the Elimination of Racial Discrimination is observed every year on 21 March. This date commemorates the Sharpeville massacre in South Africa in 1960, when police killed 69 people at a peaceful protest against apartheid. The United Nations General Assembly proclaimed the day in 1966, urging the international community to intensify efforts to eliminate all forms of racial discrimination.

The Pacific Ocean reaches its greatest depth in the Mariana Trench—about 10,920 meters below sea level—making it the deepest of the world’s oceans and covering more than 63 million square miles.