Which of the following solid salt on heating with K2Cr2O7 and Conc. H2SO4 orange,red vapours are evolved which turn aquous NaOH solution yellow?
Fe is made passive by :
(a) dil . H2SO4
(b) dil. HCl
(c) Conc. HNO3
(d) Conc. H2SO4
Which of the following element does not show the variable oxidation state?
Cr2O72-+XCr3++H2O + oxidized product of X, X in the above reaction cannot be