Science Answer the following question.

• Powder coating is a method of applying a layer harder than paint on the surface of an iron object to prevent rusting.
• In this method, a polymer resin, a pigment and some other ingredients are melt, mixed, cooled and ground into a uniform powder.
• This powder is sprayed on the polished metal surface by electrostatic spray deposition (ESD).
• In this method, the particles of the powder are given an electrostatic charge due to which a uniform layer of the powder sticks to the metal surface.
• Then the object is heated in the oven along with the coating.
• A chemical reaction occurs in the layer, resulting in the formation of long cross-linked polymeric chains.
• This powder coating is highly durable, hard and attractive.
• Powder coating can be done on plastic and medium density fibre (MDF) board in day to day use as well.

• Body odour is caused by the bacterial decomposition of the sweat. A deodorant is used to prevent this odour.
• Deodorants contain parabens (methyl, ethyl, propyl, benzyl and butyl) and also alcohol in large proportions. Aluminium compounds and silica are also used.
• Types of deodorants are :
  (a) Ordinary deo: It contains a smaller proportion of aluminium. It decreases the odour of the sweat.
  (b) Antiperspirant deo : This decreases the extent of sweating. It contains about 15% of aluminium chlorohydrate. It clogs the sweat pores on the skin.
  (c) Clinical deo : Some people sweat heavily and it has harmful effects on the skin. Clinical deo is meant for such people. It contains 20 to 25% aluminium. It is used during the night.

• The central nervous system is affected by radioactive radiations.
• Hereditary defects are generated by bombardment of radiation on D.N.A in the body.
• Radioactive radiation can penetrate the skin, and causes diseases like skin cancer, leukemia.
• The radiative pollutants created due to explosions enter the body through air and it is difficult to control them.
• The radioactive pollutants released in the sea enter the bodies of fishes and through them enter the human body.
• The radioactive paint on the watch can cause cancer.
• The radioactive isotopes strontium-90 can enter the body through plants, fruits, flowers, cereals, milk, etc. and cause diseases like bone cancer, leukemia.

• Polycythemia: The red blood cell count increases in the disease polycythemia. Phosphorus- 32 is used in its treatment.
• Bone cancer: Strontium-89, strontium-90, samarium-153 and radium-223 are used in the treatment of bone cancer.
• Hyperthyroidism: Enlargement of thyroid gland, weight loss in spite of appetite, insomnia are the symptoms of hyperthyroidism.
• It occurs due to overproduction of hormones by the thyroid gland. Iodine-123 is used in the treatment of hyperthyroidism.
• Tumour detection: Boron-10, iodine-131, cobalt-60 are used in the treatment of brain tumour, while arsenic-74 is used in detection of small tumours in the body.

• When radioactive radiations are allowed to pass through two oppositely charged plates they get separated. This method was introduced by Rutherford in 1902.
• Rutherford and Willard studied the radiation emitted by radioactive substances.
• For this purpose, the rays were allowed to pass through an electrical field and a photographic plate was held in their path.
• It was found that the radiation was divided into three types.
• One type of radiation deviated slightly towards the negatively charged plate, while the second type of radiation deviated substantially towards the positively charged plate.
• However, the third type of radiation did not deviate at all in the electrical field.
• The rays which deviated slightly toward negatively charged plate are called alpha rays.
• Those which deviate substantially towards the positively charged plate are called beta rays and those which did not deviate at all are called gamma rays.

• A protective layer is formed naturally on the surface of aluminium metal by reaction with oxygen in air.
• In the anodizing process, this layer can be made of the desired thickness.
• Anodizing is done by electrolysis.
• Dilute sulphuric acid is taken in the electrolytic cell and the aluminium article is dipped in it as the anode.
• When an electric current is passed, hydrogen gas is released at the cathode and oxygen gas at the anode.
• A reaction with oxygen occurs and a layer of hydrated aluminium oxide is formed on the anode, i.e. the aluminium article.
• This layer can be made attractive by adding colour in the cell during electrolysis.

• Food colours are mixed in most soft drinks and foodstuffs available in the market.
• These food colours are in the form of powders, gels and pastes.
• Food colours are used in domestic as well as commercial products.
• Certain colours and essences are added to ice cream, ice candies, sauces, fruit juices, cold drinks, pickles, jams and jellies.
• Food colours are often found to be added to packaged meat (chicken, mutton), chilli powder, turmeric, sweets and other similar substances so as to give them a good colour.
• Food colours are natural as well as artificial.
• The food colours prepared from seeds, beetroot, flowers and fruit concentrate are natural.
• Tetrazene, sunset yellow are artificial food colours used extensively.
• However, over-consumption of artificial food colours can be detrimental to health. Therefore, usage of natural food colours is always good.

• On 26th April 1986, the graphite reactor in the Chernobyl atomic power plant exploded, and suddenly the radioactive isotopes and radiation came out.
• Due to this episode, radioactive isotopes entered the human body through water and land and caused genetic disorders.
• These got carried further into the next generation.
• Thyroid disorders increased in children as well as adults.
• As a result, the incidence of throat diseases is greater there than in other places.

• Long before pure chemicals were manufactured in labs, people used plants for medicine.
• There are over a hundred active ingredients derived from plants for use as drugs and medicines.
• The emergence of synthetic chemistry in the 1800s opened up new avenues for scientific research into drugs.
• Many chemists tried to locate medically active ingredients in plants (for instance the important malaria remedy quinine), and subsequently tried to make those substances in the laboratory in order to become independent of plant supplies.
• At the same time, a new industry developed as scientists developed processes to synthesise new chemicals on a large scale.
• New production methods developed in the late 1800s and early 1900s made it easier to standardise, package and transport medicines.

• In the pH scale, the pH of solutions varies from 0 to 14 in accordance with the strength of the acids or base.
• The pH scale shows different colours at different values of pH. Colour from dark red to yellow or from pH value 0 to 6 indicates the substances are acidic.
• Colour from light blue to violet or from pH value 8 to 14 indicates the substances are basic.
• Green colour or pH value 7 indicates the substances are neutral.

• Dyeing hair can have adverse effects like hair fall, damage to hair texture, burning of skin, adverse effect on eyes, etc.
• Lipstick contains a dye named carmine. It does not affect lips but causes stomach disorders.
• Excessive use of plants for making natural dyes results in deterioration of the environment.

(b) Artificial food colour:

• Food colours added to pickles, jams and sauces contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
• Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

(c) Radioactive substances :

• The central nervous system is affected by radioactive radiations.
• Hereditary defects are generated by bombardment of radiation on D.N.A in the body.
• Radioactive radiation can penetrate the skin, and causes diseases like skin cancer, leukemia.
• The radioactive pollutants created due to explosions enter the body through air and it is difficult to control them.
• The radioactive pollutants released in the sea enter the bodies of fishes and through them enter the human body.
• The radioactive paint on the watch can cause cancer.
• The radioactive isotopes strontium-90 can enter the body through plants, fruits, flowers, cereals, milk, etc. and cause diseases like bone cancer, leukemia.

(d) Deodorant:

• Aluminium – Zirconium compounds are the most harmful chemicals in the deodorant. Disorders like headache, asthma, respiratory disorders, heart disease are likely to occur without our knowledge.
• There is a possibility of various skin disorders and also skin cancer due to the aluminium chlorohydrates.

• Food colours are mixed in most soft drinks and foodstuffs available in the market.
• These food colours are in the form of powders, gels and pastes.
• Food colours are used in domestic as well as commercial products.
• Certain colours and essences are added to ice cream, ice candies, sauce, fruit juices, cold drinks, pickles, jams and jelly.
• Food colours are often found to be added to packaged meat (chicken, mutton), chilli powder, turmeric, sweets and other similar substances so as to give them a good colour.
• Tetrazene, sunset yellow are artificial food colours used extensively.

(b) Harmful effects of artificial food colours

1. Food colours added to pickles, jam and sauce contain small quantities of lead and mercury. These can be harmful for those who consume these products on a regular basis.
2. Diseases like ADHD (Attention Deficit Hyperactivity Disorder) can affect children due to excessive consumption of foods with added food colours.

• The atmosphere, rain water and chemical substances have no effect on Teflon.
• Neither water nor oil will stick to Teflon coated articles.
• High temperatures do not affect Teflon as its melting point is 327 °C.
• Teflon coated articles are easy to clean.
• Teflon is a poor conductor of electricity.

• We regularly use artificial colours on Rang Panchami.
• The red colour used on Rang Panchami is very dangerous. It contains a high proportion of mercury in it.
• This poses risks like blindness, skin cancer, asthma, itching of the skin, permanent blocking of sweat pores, etc.
• Therefore, it is necessary to use eco-friendly colours.
• We will prepare colours for Rang Panchami from natural resources such as beet root, flowers of flame of forest, spinach, flame tree (gulmohar) and protect your health by using these.

• The atmosphere and chemical substances have no effect on Teflon.
• Neither water nor oil will stick to Teflon coated articles.
• High temperatures do not affect Teflon as its melting point is 327 °C.
• Teflon coated articles are easy to clean.

• Internal cracks and voids in cast iron articles and iron solder can be detected with the help of gamma rays.
• For this purpose, isotopes like cobalt-60, iridium-192 are used in the radiography camera.
• This technique is used for detecting flaws in metal work.

Measurement of thickness, density and level

• It is necessary to maintain the required thickness in the manufacture of aluminium, plastic, iron sheets of differing thickness.
• In the manufacturing process, a radioactive substance is placed on one side and an instrument to measure radiation on the other.
• The radiation read by the measuring instrument varies with the thickness of the sheet.
• Material inside a packing can also be examined by the same technique.

Luminescent paint and radio luminescence:

• The radioactive substances radium, promethium, tritium with some phosphor are used to make certain objects visible in the dark, for example, the hands of a clock, and certain other objects.
• Krypton-85 is used in HID (High-Intensity Discharge) lamps while promethium – 147 is used in portable X-ray units as the source of beta rays.

Use in Ceramic articles:

• Luminous colours are used to decorate ceramic tiles, utensils, plates, etc.
• Earlier uranium oxide was used in these paints.