Science
- The particles of powder are given an electric charge while spraying them to form the powder coating. 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 poly... 1
- Soap forms a precipitate in hard water. When soap is added to hard water, the displacement of sodium takes place and calcium, magnesium salts of fatty acid are formed. Since these... 1
- The hard water of a well becomes soft on adding washing soda to it. The hardness of hard water is due to the presence of chlorides and sulphates of calcium and magnesium. When washing soda (Na₂CO₃. 10H₂O) is... 1
- Bleaching powder has the odour of chlorine. Chlorine is the main constituent of bleaching powder. When exposed to air, bleaching powder reacts with carbon dioxide in air to produce cal... 1
- Why has the use of methods like Teflon coating become more common? Teflon is a substance which is inert to chemicals, stable at higher temperatures, easy to clean and nonstick. All these properties make it a... 1
- What type of colours will you use to celebrate ecofriendly Rang Panchami? Why? We should use natural colours made from plants for celebrating an echo friendly Rang Panchami. These natural colours can be made from natura... 1
- Write down properties of teflon. Teflon has the following properties: It is not influenced by the atmosphere and chemical substances both water and oil do not stick to the T... 1
- Where in the industrial field is radioactivity used? Radioactivity has various industrial application: It is used as a fuel in nuclear reactors to generate power. Internal cracks and voids in c... 1
- Which diseases are caused by artificial food colours ? Colours used in pickles, jam and sauces contain lead and mercury in small quantities. Regular consumption of these products can be dangerous... 1
- When is said to be the nucleus unstable? Nucleus of certain elements such as uranium, thorium, radium etc. have a property of spontaneously emitting invisible, highly penetrating an... 1
- What is meant by radioactivity? Elements with a high atomic number such as uranium, thorium, radium have a property of spontaneously emitting invisible, high penetrating an... 1
- Match the pairs Saturated brine a. sodium metal free Group A Group B 1. Saturated brine c. crystallization of salt 2. Fused salt a. sodium metal free 3. CaOCl₂ d. oxidation of colour 4. NaHCO₃... 1
- Fill in the blanks . 1. The number of molecules of water of crystallization in washing soda is 10. 2. The chemical name of baking soda is sodium bicarbonate. 3.... 2
- How will you prove experimentally that the graphite is a good conductor of electricity. The following experiment should be performed to check whether graphite is good conductor or not. When we use two graphite ends of pencil in... 1
- What are the different types of coal? What are their uses. The different types of coal are peat, lignite, bituminous, anthracite etc. uses :: Lignite is used in the generation of electricity. Bitumin... 1
- Write two physical properties of each. a) Diamond b) Charcoal: c) Fullerenes: a) Diamond: Diamond is the allotropes of carbon which is hardest in teh nature. It is colourless, transparent and brittle in pure form. b) C... 1
- Practical uses of CO2. CO₂ is mainly used in making aerated drinks. Solid carbon dioxide is used to make milk and it’s products cool during the transportation. In... 1
- Use of CO2 in the fire extinguisher. Carbon dioxide is used in the fire extinguisher as it has cooling effect at high pressure. Also it removes the oxygen which is necessary for... 1
- Uses of various allotropes of carbon. There are various allotropes of carbon which are used in many ways. Diamond is used in cutting glasses and in drilling machines. It is used... 1
- Petrol, diesel, coal are fossil fuels. Petrol, diesel, coal are the fossil fuels as they are obtained from the dead plants and animals. These fossil fuels are formed when the aqua... 1
- Methane is called as marsh gas. Methane is used as the marsh gas because it is mostly occuring at the marshy places which are the lands surrounded by water for long period... 1
- Diamond, graphite and fullerenes are crystalline forms of carbon. As we know that, carbon has the property of allotropy. That means it has three allotropes namely diamond, graphite and fullerenes. These are... 1
- GIve scientific reason Biogas is an eco-friendly fuel. Biogas is formed by the decomposition of animal dung, dry leaves, wet garbage in a biogas plant. This produces methane gas also called bioga... 1
- Give scientific reason Limewater turns milky when CO2 is passed through it. Limewater traditionally means a weak solution of the alkali calcium hydroxide Ca(OH)2. When CO2 is passed through limewater, it reacts with... 1