Because the formation of rust is a kind of chemistry reaction.
After chemistry reaction, compound with new properties is produced.
Of course, color is one of the new properties.
For example, if you put iron in colorless acid solution, a green solution is made.
This kind of chemisty reaction differs from physical reaction, for example, pigment with one color dissolves in liquid, a liquid with same color is made.
In a 0.01 M solution of HCl, Litmus will be red. Litmus paper will turn into red in acidic conditions. Hydrochloric acid is an acid. Litmus is an indicator for acidity and alkalinity made from inchens.
A solution is turning blue means, it is turning it's behavior to Basic from Acidic. Reagent D must be a Basic component so it is increasing the pH of the solution. As reaction does not depend on the phase of the component, it could be anything i.e., Solid, Liquid or gas.
Hope this helps!
The atoms are all electrically neutral because the number of protons is equal to the number of electrons.
<h3>What is electrical neutrality?</h3>
An atom is electrically neutral when the number of protons is equal to the number of electrons.
In the cases of H-1, H-2, and H-3, the nuclides have one electron an one proton. The different mass numbers arise from differences in the number of neutrons. Hence in all cases, the nuclides are electrically neutral.
Learn more about neutral atoms:brainly.com/question/5308494
#SPJ1
