It used to be silver but now the mirroring is usually aluminium.
Convex mirrors
Concave mirrors
concave mirrors are used as rear view mirrors and serve dentists and used as reflectors
convex mirrors are used in vehicles because convex mirrors make things look bigger which will be easy for the drivers.
They use convex mirrors to give a wider view.
silver
Silver is used for all these. Gold could be, but silver is more likely to be used in electrical circuits and for mirrors.
Silver
Mercury WAS used for mirrors- it provided a bright reflection that did not tarnish.
Convex mirrors
Concave mirrors
Concave mirrors are used in telescopes. Convex mirrors are used as side-view mirrors in cars.
concave mirrors are used as rear view mirrors and serve dentists and used as reflectors
silver is used in making mirrors because silver has a property to reflect so it is used in making mirrors
convex mirrors are used in vehicles because convex mirrors make things look bigger which will be easy for the drivers.
Convex mirrors
Side view mirrors.