NCERT Solution for Class 10 Science Chapter 1
Chemical Reactions and Equations
Exercises Questions
Page No-16
Questions No-17
A shiny brown coloured element ‘X’ on heating in air becomes black in colour. Name the element ‘X’ and the black coloured compound formed.
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The brown coloured element ‘X’ is copper. On heating in air it forms copper oxide which is black in colour.
2Cu(s) + O2(g) → 2CuO(s)
Copper Oxygen Copper oxide
(Brown (Black)
color)
Copper is a brown coloured shiny element, when heated in air, it becomes black in colour.
2Cu+O2→2CuO
Hence, the element ‘X’ is copper and black coloured compound formed is copper oxide.
The shiny brown colored element ‘X’ that turns black when heated in air is likely to be copper (Cu). When copper is heated in the presence of oxygen (air), it undergoes oxidation and forms copper oxide (CuO), which is a black-colored compound. The reaction can be represented as follows:
2Cu(s) + O2(g) → 2CuO(s)
So, the element ‘X’ is copper (Cu), and the black-colored compound formed is copper oxide (CuO).