Turmeric (Haldi) rapidly becomes colourless on addition of

A dilute solution of litmus becomes colourless on shanking with charcoal. This is due to:

Blue coloured copper sulphate crystals become colourless n heating.

Chlorine water turns blue litmus red but solution becomes colourless after some time. Why?

In blue solution of copper sulphate excess of KCN is added then solution becomes colourless due to the formation of:

"Soldering becomes easy due to the addition of flux". Why?

"When NH_(4)SCN (colourless) is added to dilute solution of FeCl_(3) (light yellow), the colour o the solution becomes deep red but on addition of NH_(4)Cl solution (colourless) the red colour faded." Why?