Answers

2016-04-12T22:45:10+05:30
‘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.
2Cu+O2---2CuO.
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2016-04-13T12:00:32+05:30
The element x must be copper because copper is ashiny brown coloured element which on heating in air combine with o2 of the air to form black copper oxide...

2cu+02----heat---> 2cuo
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