Tag: dyes

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Questions Related to dyes

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

A colloidal solution can be purified by following the method of:

  1. dialysis

  2. peptization

  3. filtration

  4. oxidation
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

A colloidal solution can be purified by the following methods - Dialysis, Electro-dialysis and Ultrafiltration.

Hence, option A is the correct answer.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

What is the basic difference between dye and pigment?

  1. Dye is an inorganic chemical that permeates fibers

  2. Dye is held to the surface of the fiber by a resin

  3. Dye diffuses into the interior of a fiber from a water solution

  4. Dyes lays on the surface of the fiber
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The dye is known as a coloured substance which has a great affinity towards the substrate on which it is applied. The basic difference in between dye and pigment is that dye is diffused into the interior of a given fabric from its water solution whereas pigment does not.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

The dyes used in reduced state and are then oxidized in the fabric by air are called:

  1. azo dye

  2. vat dye

  3. basic dye

  4. dispersed dye
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Vat dyes can applied directly on fibre and are generally insoluble in water. These can be used only on cotton but can not be used on silk and wool. In this case  dying is a continuous process and is carried out in a large vessel called vat. For this reason these dyes are Known as vat dyes, indigo is an example of vat dyes 

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

When a dye is formed on the fiber or cloth by a chemical reaction at the time of dyeing, the process is known as:

  1. synthesis

  2. direct dyeing

  3. vat dyeing

  4. absorption
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

Direct Dye is a class of dyestuff's that are applied directly to the substrate in a neutral or alkaline bath. They produce full shades on cotton and linen without mordant and can also be applied to rayon, silk, and wool. Direct dyes give bright shades but exhibit poor wash fastness. Various after treatments are used to improve the wash fastness of direct dyes, and such dyes are referred to as 'after treated direct colors". Direct dyes are molecules that adhere to the fabric molecules without help from other chemicals.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

Indigo dye is an example of :

  1. Azo dye

  2. Vat dye

  3. Dispersed dye

  4. Basic dye
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

 Indigo dye is an example of Vat dye, These dyes can be used only on cotton it is a long continuous process which is carried out in a large vessel known as Vat. These dyes are applied directly on the fibre and are generally insoluble in water.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

Which of the following is not a natural dye of either vegetable or animal origin?

  1. Tyrian purple

  2. Indigo

  3. Saffron

  4. Azo dye
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

Azo dyes are organic compounds, which contain the coloring azo function (N=M-). The azo function is often bound to an aromatic ring, and the dye can then be broken down to an aromatic amine, arylamine. This can take place either chemically, through reductive cleavage, or through the body's own enzyme system. Some azo dyes can also be broken down to arylamines during storage due to light and high temperature. Some arylamines have been judged to be carcinogenic.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

When soap or detergent is added to water, which of the following is true?

  1. This results in formation of oil in water type emulsion.

  2. This results in formation of water in oil type emulsion.

  3. This results in formation of either oil in water type emulsion or water in oil type emulsion.

  4. No emulsion is formed.
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

When soap or detergent is added to water, this results in the formation of oil in water type emulsion.
The polar water-soluble ( hydrophilic) head is on the surface of the micelle whereas non-polar oil soluble (hydrophobic) tail is in the centre of the micelle. In the centre of the micelle, small oil droplets are present in which hydrophobic part of micelle dissolves.

Multiple choice dyes dyes and pigments chemistry in daily life applied chemistry chemistry

In coloured photography, the colour film is developed by oxidation of the developer and then reacting with:

  1. an alkai to form a salt

  2. a coupler to form a dye

  3. an acid to form a salt

  4. a metal to form a pigment
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

The development step uses reducing chemicals, and the exposed silver-halide grains develop to pure silver. The oxidized developer is produced in this reaction, and the oxidized developer reacts with chemicals called couplers in each of the image-forming layers. This reaction causes the coupler to form a color, and this color varies depending on how the silver-halide grains were spectrally sensitized. A different color-forming coupler is used in the red, green, and blue sensitive layers. The latent image in the different layers forms a different colored dye when the film is developed.