In making gun-barrel,the steel used is

Which of the following aqueous solutions absorbs nitric oxide in significant amounts?

The conductivity and appearance of $CrO_2$ are like metallic $Cu$.

Copper sulphate is not used:

Provide the structures of the following ions:
$1.$ $CrO_4^{2-}$
$2.$ $Cr_2O_7^{2-}$

An acidified solution of potassium chromate was layered with an equal volume of amyl alcohol. When it was shaken after the addition of $1 \ mL$ of $3 \% \ H_2O_2$,a blue alcohol layer was obtained. The blue color is due to the formation of a chromium$(VI)$ compound '$X$'. What is the number of oxygen atoms bonded to chromium through only single bonds in a molecule of $X$ ?