Tag: dyes

Questions Related to dyes

Which type of dyes are not used to dye nylon and polyester fibres?

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. Vat dyes

  2. Basic dyes

  3. Disperse dyes

  4. Insoluble azo dyes

Show answer
Correct Option: A
Explanation:

Vat dyes are not used to dye nylon and polyester fibres but used to dye cotton fibres. 


Basic dyes disperse dyes and insoluble azo dyes are used to dye nylon and polyesters.

If  greater the number the double bonds in the carotenoid dyes is more :

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. the more water soluble it is

  2. the more non-water insoluble it is

  3. the more intense or darker the pigment will be

  4. the weaker the dye color will be

Show answer
Correct Option: C
Explanation:

If more number of double bonds are present in the carotenoid system the intensity or the darkness of the pigment will increases.
Hence option C is correct.

Which of the following are natural dyes:

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. alizarin, carminic acid and tartrazine

  2. indigo, bixin and alizarin

  3. tartrazine, FD&C Blue #1, and indigo

  4. chlorophyll, yellow #6 and haematin

Show answer
Correct Option: B
Explanation:

Natural dyes are dyes derived from animal or plant material without any chemical treatment. They are obtained from sources like flowers,
leaves, insects, bark roots etc.; however, they are not readily
available and involve an extraction process.In th above question and the natural dyes are indigo, bixin and alizarin.
Hence option B is correct.

Which of the following is the characteristic property of a vat dye

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. must be reduced to a soluble form so that it can dissolve in the dye bath and get Be trapped in the cellulose fiber.

  2. penetrates both the outer ring and the inner core of a piece of fiber.

  3. Remains in its soluble form inside the denim fabric.

  4. Must be in an insoluble form so that it can get trapped in the cellulose fiber.

Show answer
Correct Option: D
Explanation:

Vat dyes are essentially insoluble in water and incapable of dyeing fibers
directly. However, reduction in alkaline liquor produces the water-soluble
alkali metal salt of the dye, which, in this leuco form, has an affinity for
the textile fiber. Subsequent oxidation reforms the original insoluble dye. The
color of denim is due to indigo, the original vat dye
So a vat dye must be reduced to a soluble form so that it can dissolve in the dye bath and get trapped in the cellulose fiber.
Hence option D is correct

Match metal ion (Part I) with colour (Part II) in presence of alizarin:


  Part I   Part II
I. ${ Sn }^{ 2+ }$ A. Blue
II. ${ Mg }^{ 2+ }$ B. Pink
III. ${ Al }^{ 3+ }$ C. Violet
IV. ${ Ba }^{ 2+ }$ D. Red

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. I-A II-D III-C IV-B

  2. I-B II-A III-D IV-C

  3. I-C II-B III-A IV-D

  4. I-D II-C III-B IV-A

Show answer
Correct Option: B
Explanation:
$Alizarin$ is a typical mordant dye gives different colours with metal ions as some of them are given below: 

$Al^{3+} \Rightarrow Red$
$Sn^{2+}  \Rightarrow Pink$
$Ba^{2+} \Rightarrow Voilet$
$Mg^{2+} \Rightarrow Blue$

Option B is correct.

The Mordant is:

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. a dye color that bites into the fiber.

  2. a metallic ion that attaches to fibers and causes a color emission.
    a chemical that stops the dye process.

  3. a metallic ion or salt added to the dye bath to make dyes less colorfast by forming a bridge between the dye and the fiber.

  4. None of these

Show answer
Correct Option: C
Explanation:

A mordant or dye fixative is a substance used to set dyes on fabrics or tissue sections by forming a coordination complex with the dye which is then attached to the fabric or tissue.

[1] It may be used for dyeing fabrics, or for intensifying stains in a cell or tissue preparations. 
it was thought that a mordant helped the dye bite onto the fibre so that it
would hold fast during washing. A mordant is often a polyvalent metal ion.

[2] The resulting coordination complex of dye and ion is colloidal and can be either acidic or alkaline. So a mordant is a metallic ion or salt added to the dye bath to make dyes more colourfast by forming a bridge between the dye and the fibre.

Hence option D is correct.

Dyes in litmus are made from:

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. mycorrhizae

  2. rhizoids

  3. lichens

  4. algae

Show answer
Correct Option: C
Explanation:
A water-soluble mixture which is a combination of different type of dyes which are extracted from lichens is known as litmus. This litmus is absorbed on filter paper to made one form of pH indicator, used to test the acidity or basicity of substances. 

If  greater the number the double bonds in the carotenoid dyes is more :

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. The more water soluble it is.

  2. The more non-water insoluble it is.

  3. The more intense or darker the pigment will be.

  4. The weaker the dye color will be.

Show answer
Correct Option: C
Explanation:

If more number of double bonds are present in the carotenoid system the intensity or the darkness of the pigment will increases.
Hence option C is correct.

The first dye that was prepared synthetically was:

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. Mauveine

  2. Azo-dyes

  3. Malachite green

  4. Phthalein dyes

Show answer
Correct Option: A
Explanation:

(A) Mauveine

Mauveine, also known as aniline purple and Perkin's mauve, was the first synthetic dye. It was discovered serendipitously by William Henry Perkin in 1856. It is also among the first dyes to have been mass-produced.

The chemical part of the dye that absorbs light and produces colour is called a :

dyes dyes and pigments chemistry in daily life applied chemistry chemistry

  1. natural pigment

  2. chromophore

  3. neon

  4. photochrome

Show answer
Correct Option: B
Explanation:
A chromophore is a group of atoms which control the colour of the dye. Thus option B is the correct answer.