Solution:
Al2O3 is used as adsorbent in chromatography. Thus, metal 'M' is Al.
When metal 'M' is treated with NaOH, a white gelatinous precipitate 'X' is obtained, which is soluble in excess of NaOH. Compound 'X' when heated strongly gives an oxide which is used in chromatography as an adsorbent. The metal 'M' is:
Al2O3 is used as adsorbent in chromatography. Thus, metal 'M' is Al.