Questions

A search engine is a set of programs which enables users to search documents and files ihe world wide web.

Common search engines are Google, Yahoo, Bing,...

A homepage is a main or starting page of a website from where we can go to the individual pages by clicking the urls in it.

Inhaling of oxygen and releasing of carbon dioxide to make our living is the process called as respiration. We know that, air is a mixture several gases like 78% of nitrogen, 21% of oxygen and several other gases with watervapour.

Hence, Oxygen is essential for respiration process.

When exposed to certain frequencies of radiation, such as radio waves, the subatomic particles called electrons that orbit an atom's nucleus will "jump" back and forth between energy states. Clocks based on this jumping within atoms can therefore provide an extremely precise way to count seconds.It is no surprise then that the international standard for the length of one second is based on atoms. Since 1967, the official definition of a second is 9,192,631,770 cycles of the radiation that gets an atom of the element called caesium to vibrate between two energy states.