A shiny brown -coloured elemnt 'X' on heating in air becomes black in colour. Name the element 'X' and the black - coloured compound formed.

Explanation

X . is copper (Cu) and the black-coloured compound formed is. copper oxide (CuO). The equation of the reaction involved on heating copper is given below.
`underset("Shiny brown in colour")(2Cu+O_2(g))overset("Heat")tounderset("Black in colour")(2CuO)`