Science
- Explain chemical co-ordination in humans and give the names and functions of some hormones. Answer: Chemical co-ordination in humans is carried out by hormones secreted by endocrine (ductless) glands directly into the blood, which c... 1
- write note on Reflex action Reflex action is an immediate and involuntary response given to a stimulus from the environment. The reflex action is so spontaneous that it d... 1
- write notes on Human brain Human brain is highly evolved organ. It is the main controlling centre of nervous system. It is the part of the central nervous system. It i... 1
- write notes on nerve cell Nerve cell- Nerve cells are also known as neurons. Neurons or nerve cells are structural and functional units of the nervous system that car... 1
- write notes on Transpiration There are stomata on the leaves of the plants. Through these opening the excess of water is thrown out in the form of water vapours. This pr... 1
- Write notes on Root pressure The pressure created in the root cells is called a root pressure. Root cells are in contact with water and minerals in the soil. But the con... 1
- Complete the paragraph. The milk was on the stove. The milk was on the stove. Rasika was engrossed watching television. She smelled something burning. She ran towards the kitchen. The milk wa... 1
- Match the pairs and explain. ‘A’ ‘B’ 1. Growth of pollen tube towards ovule b. Chemotropic movement 2. Growth of shoot system c. Phototropic movement 3. Growth of root s... 1
- write harmfull effect of Deodorant It contains aluminium – zirconium compounds which are the most harmful chemicals in the deodorant. They can result in the development of dis... 1
- Write the harmful effects Radioactive substances Radioactive substances affect the central nervous system. Exposure to radioactive radiations for long periods can lead to hereditary defects... 1
- Write the harmful effects Artificial food colour Colours used in pickles, jam and sauces contain lead and mercury in small quantities. Regular consumption of these products can be dangerous... 1
- Write the harmful effects Artificial dye Use of dye for dyeing hair can have adverse effects like hair fall, damage to hair texture, burning of skin. The dyes used for dyeing hair h... 1
- Write the chemical formula Bleaching powder, common salt, baking soda, washing soda The chemical formula of bleaching Powder is CaOCl₂. The chemical formula of common salt is NaCl The chemical formula of baking soda is NaHCO... 1
- Explain what you see in the following picture This picture shows the process of powder coating. A polymer resin, a pigment and some more ingredients are melted, mixed, cooled and ground... 1
- write uses of Ceramic They are used in making roofing tiles, construction bricks, pottery, terracotta etc. Special type of ceramics are used in outer surfaces of... 1
- write uses of Radioactive substances It is used as a fuel in nuclear reactors to generate power. It is used in controlling the thickness of paper, plastic and metal sheets durin... 1
- Write uses of Powder coating It makes painted architectural steel parts resistant to heat damage, cold damage and even corrosion. Most of metal products designed to be u... 1
- Write the uses of Anodizing Anodizied cooking utensils like griddles cookers and pans are nonstick, scratch resistant and can be easily cleaned. Anodized utensils are h... 2
- Write briefly about the three methods of electrolysis of sodium chloride. When an electric current is passed through a saturated solution of sodium chloride (brine) it is electrolysed and hydrogen gas is released a... 1
- What is meant by water of crystallization? Give examples of salts with water of crystallization, and their uses. Water of crystallization is a fixed number of water molecules present in the crystal structure. Substances in our daily use which contain sa... 1
- Write about artificial food colours, the substances used in them and their harmful effects. Artificial food colours used for : For Red colour : Ponceau 4 R, carmoisine and erythrosine. For yellow colour : tetrazene and sunset yellow... 1
- A certain type of ceramic tiles are fixed on the outer layer of a space shuttle. A certain type of ceramic tiles are fixed on the outer layer of a space shuttle. They are made from alumina (Al₂O₃), zirconia (ZrO₂), silica... 2
- When the radiation coming out from certain radioactive substance is passed through an electric field, When the radiation coming out from certain radioactive substance is passed through an electric field, marks of three distinct spot are found... 1
- The aluminium article is used as an anode in the anodising process. A protective layer is formed naturally on the surface of aluminium metal by reaction with oxygen in air. In the anodizing process, this laye... 1