Question

Match column 1 with column 2 for the following given.

Column 1	Column 2
\[FeS{0_4}.7{H_2}O\]	Green
\[NiC{l_2}.4{H_2}O\]	Light pink
\[MnC{l_2}.4{H_2}O\]	Blue
\[CoC{l_2}.6{H_2}O\]	Pale green
\[C{u_2}C{l_2}\]	Pink
	Colorless

Answer 1

Hint: We must have to know that all the compounds given contain transition metals which are also known as d block elements. They are placed in the middle of s and p block elements and above f block elements. The color of any compound arises due to transitions.

Complete answer:
We will answer this question by giving correct color for the compound given in column 1 in its order only. Also the color is formed due to water crystallization. Let’s start with first which is \[FeS{0_4}.7{H_2}O\] this is also known as anhydrous ferrous sulphate or ferrous sulphate heptahydrate, it is pale green in color as it lose water of crystallization. Next is \[NiC{l_2}.4{H_2}O\] it is known as nickel chloride and it’s green in color. We must remember that the \[MnC{l_2}.4{H_2}O\] is light pink in color since it forms d-d transitions. Next is \[CoC{l_2}.6{H_2}O\], in moisture cobalt chloride changes its color from sky blue to pink, the chemical name for this compound is Cobalt chloride hexahydrate. Last is \[C{u_2}C{l_2}\] it has a chemical name cupric chloride and it is colorless due to absence of paired electrons.

Note:
We have to remember that the color of the compound is due to many factors. A compound is colored if it has unpaired electrons in it; when d-d transitions occur metal will show color in them due to different transitions or movement of electrons to excited levels. We must have to remember that every element has a line emission spectrum which is defined thus color can be identified for any compound.