Sonali was performing a experiment in which metal X which was of reddish brown colour, when heated in the presence of oxygen it forms a black coloured compound Y which was basic in nature. When this is again heated in the presence of hydrogen gas it gives back the substance X. Identify the X and Y?

Q. A brown and bright element $X$ when heated in presence of air turns in to black substance $Y$. If Hydrogen gas is passed over this heating material, again $X$ is obatined. $X$ and $Y$ respectively are:

Q. A Brown and bright element "x" when heated in presence of air turns in to blacks substance "y". If Hydrogen gas is passed over this heating material again "x" is obtained. "x" and "y" are

Q. A brown and bright element 'X' when heated in presence of air turns into black substance 'Y'. If hydrogen gas is passed over this heating material again 'X' is obtained 'X' and 'Y' are -

Q. A shiny brown coloured element $\text{X}$, when heated in the air, forms a black coloured compound $\text{Y}$. Identify $\text{X}$ and $\text{Y}$.

Q. Rashi was performing an experiment. She mixed a compound X with water in a beaker. She found that the beaker was becoming hot, releasing heat and forming a new substance Y. She was shocked and left the room leaving the product. After three-four days when she returned, she found that the substance Y has changed into a shiny substance Z. What are X, Y and Z.