Rafael Nadal defeated Daniil Medvedev in the men's singles title at the 2019 US Open. It was Nadal's 19th Grand Slam singles title, and fourth US Open title.

Galton's whistle is also called as Dogs whistle or silent whistle, is a type of whistle that emits sound in the ultrasonic range, which people cannot hear but some other animals can, including dogs and domestic cats, and is used in their training.

The Right of Children to Free and Compulsory Education Act or Right to Education Act (RTE) which describes the importance of free and compulsory education for children between 6 and 14 in India is enacted under Article 21A of the Indian Constitution.

Our Ex. Prime Minister Rajiv Gandhi was Pilot by profession before he entered politics.

Kolkata Metro Rail is the first metro rail operating since 1984 in India.

The world’s largest tropical rainforest Amazon rain forests are called "Lungs of the Earth". It is so called because it produces 20% of the Earth's oxygen, and is also a vast carbon sink, absorbs more than 1 billion tons of atmospheric carbon which is emitted by the burning of fossil fuels annually.