661. Oxidation is a chemical reaction involving the loss of electrons.
662. According to the Big Bang Theory, the Universe began about 10-20 billion years ago.
663. Meteorology is the study of the atmosphere.
664. The instrument used to measure wind speed is an anemometer.
665. The device used to convert Alternating Current into Direct Current is a rectifier.
666. Hummingbirds belong to a category called endotherms.
667. A person with blood group AB+ is considered the universal recipient.
668. The drug abuse involving the most risk of infection with the HIV virus is injection of heroin.
669. Steel has the maximum calorific value among the given options.
670. The number of spark plugs needed in a diesel engine is 0.
671. The ozone layer prevents ultraviolet radiation from entering the atmosphere.
672. In winter, an iron pipe feels colder than a wooden window because wood is a non-conductor.
673. The temperature of a dead body is the temperature of the place where it is kept.
674. The instrument specially designed for recording earthquake waves is a seismograph, which measures earthquakes on the Richter scale.
675. The main component of bones and teeth is calcium phosphate.
676. Fats have the maximum calorific value among the given options.
677. The sun appears red at sunrise and sunset due to scattering of light.
678. The rear-view mirror of a motor vehicle is convex.
679. The absorption of ink by blotting paper involves capillary action phenomenon.
680. Albatross is a sea bird.