Question

With which of the following cations, alizarin will impart a violet colour on the fabrics?
(A) $ M{{g}^{2+}} $
(B) $ C{{r}^{3+}} $
(C) $ B{{a}^{2+}} $
(D) $ A{{l}^{3+}} $

Answer 1

Hint :We know that Alizarin is a mordant dye which is mainly used in dyeing purposes. It is also used in hand block printing technique. Alizarin is used in biochemical assay for the quantitative determination of the presence of calcific deposition by the cells of an osteogenic lineage by colorimetry.

Complete Step By Step Answer:
Alizarin is an organic compound whose chemical formula is also known as dihydroxyanthraquinone), Mordant red eleven that has been used throughout history as a prominent red dye especially for dyeing textile fabrics. Initially, it was derived from the roots of plants of the madder genus; it became the first natural dye to be produced synthetically. It is known by different names such as Alizarin B, Alizarin red, Turkey red, etc. It is slightly soluble in water. The word Alizarin is the most common term for the dye that has deep red colour but it is also used for the several non red dyes such as Alizarin Cyanine Green and Alizarin Brilliant blue.
The most important use of alizarin in modern times is as a staining agent in biological research because it stains free calcium and certain calcium compounds. Alizarin continues to be used commercially as a red textile dye but to a lesser extent than in the past. A mordant dye is a substance which is used to set or bind dyes on fabrics by forming a coordination complex with the dye that gets attached to the fabric. It is used to stain synovial fluid while testing it for the presence of basic calcium phosphate crystals. It also has various applications in the field of geology where it is used to indicate the minerals of calcium carbonate, like calcite and aragonite. Alizarin gives brown red with $ C{{r}^{+3}},Cr\left( 3+ \right) $ rose red with $ A{{l}^{+3}}\text{,}Al\left( 3+ \right) $ blue with $ B{{a}^{+2}}\text{,}Ba\left( 2+ \right) $ violet with $ M{{g}^{+2}}\text{,}Mg\left( 2+ \right) $ and red with $ S{{r}^{+2}}\text{,}Sr\left( 2+ \right) $ ions.
Therefore, the correct answer is option A.

Note :
Remember that the mordant is a substance that is used in combination with a dye to carry out the dying process. It may be used for either dyeing of fabrics or for the intensification of stains in cells and tissues. A mordant is the reason behind the formation of the coordination bond that attaches the dye to the fabrics.