Title E-Science-EM10_001-054.pdf ✅

2 SCIENCE [011] ANSWERS TO QUESTION PAPER 2 Section A 11. C. Citric acid 12. B. – COOH 13. C. sieve tube and companion cell 14. B. heating effect of electric current. 15. B. F 16. A. 25 cm 17. Butanone is a four-carbon compound with ketone functional group. 18. Mendel was the first scientist to conduct systematic experiments for the study of heredity. 19. According to Joule’s law, heat energy produced in a resistor is directly proportional to the square of electric current. 10. The process of opening-closing of stomata is controlled by guard cells. 11. The unit of power of lens is diopter. 12. The purity of gold is measured in unit carat. 13. False 14. True 15. True 16. True 17. Testosterone 18. Mendel 19. (B) Ð e = angle of refraction 20. Tungston metal 21. Adrenaline Gland – At the tip of kidney 22. Pancreas – Below the stomach in the abdomen 23. Primary consumers – Herbevores 24. Secondary consumers – Carnivores Section B 25. Solution of lime water – Ca(OH)2 is used for whitewashing the walls of the house. It is prepared by slaking of lime as shown in the following reaction : CaO(s) + H2O(l) 3⁄4® Ca(OH)2(aq) Solution of slaked lime (Lime water) Solution of lime water is applied to the walls of the house, then it reacts slowly with the CO2 gas of air and a thin layer of CaCO3 is formed on walls after two to three days. As a result, walls appear shining white.
Online Answer Keys – SCIENCE 3 Ca(OH)2(aq) + CO2(g) 3⁄4® CaCO3(s) + H2O(l) Calcium Calcium hydroxide carbonate 26. Non-metals as solids : Carbon, sulphur, iodine Non-metal as liquid : Bromine (exception) Non-metals as gases : Oxygen, hydrogen, nitrogen 27. Autotrophic Nutrition Heterotrophic Nutrition 1. It occurs in green plants and some bacteria. 2. In such mode of nutrition, food is synthesised from inorganic components, i.e., CO2 and H2O. 1. It occurs in animals and fungi. 2. In such mode of nutrition food is consumed from other organisms. 28. Asexual reproduction Sexual reproduction 1. In asexual reproduction, a single individual is involved, whose certain body part forms the new individual of the same kind. 2. The sex of an organism does not play any role. 1. In sexual reproduction, two gametes of opposite sex fuse to form a fertilized egg (zygote) that develops into a new individual. 2. The organisms involved are either bisexual or the two individuals are of opposite sex. 29. The sexual act is a very intimate connection of bodies of two individuals. So, many diseases can be transmitted through sexual act. Bacterial infections : Syphilis, gonorrhoea Viral infections : Warts, HIV-AIDS Using a condom during sexual act helps to prevent transmission of many such infections to some extent. 30. ( 1 ) Name of this phenomenon is dispension of light. ( 2 ) In the XY spectrum, colour at point X is violet and colour at point Y is red. 31. The electric current is the net amount of electric charge that passes through any cross-sectional area of the conductor in unit time. ® I = t Q ® The SI unit of electric current is coulomb / second (C / s) or ampere (A). 32. Total power P = 100 W (electric bulb) + 500 W (refrigerator) = 600 W Consumption of both the devices in 10 days (in hours) = 12 hour days * 10 days = 120 h \ Total energy consumed = p * t = 600 W * 120 h = 72,000 Wh = 72 kWh \ Expense = 72 kWh * M 8 = M 576
4 GALA MODEL QUESTION PAPERS : STANDARD 10 (2025) 33. Direct Current (DC) Alternating Current (AC) 1. It flows only in one direction. 2. It is obtained with a cell / battery or a DC generator. 1. Its direction is reversed at regular intervals of time. 2. It is obtained with an AC generator. 34. ( 1 ) a – carnivores Categories : Primary carnivores and higher carnivores ( 2 ) b – Decomposers (Bacteria and Fungus) Function : They decompose the complex organic substance present in dead bodies and excretory matters in simple inorganic substances. 35. Pesticides and other chemicals are used in order to protect the crops from diseases or pests. Such chemicals are non-biodegradable. The amount of these chemicals increases in the soil or water bodies due to uncontrolled use of it. From soil or water they enter in the body of plants and then it passes in trophic levels of food chain. They get accumulated progressively at each trophic level as these chemicals are not degradable. Due to biomagnification, high concentration of such chemical causes lethal effects on higher level carnivores animals. Some such chemicals prove lethal for organisms of lower trophic level too. These chemicals reach upto human beings too through food. Thus, it is necessary to prevent the uncontrolled use of pesticides and other chemicals. 36. ( 1 ) x – Stomata. Exchanges of gases and process of transpiration occur by them. ( 2 ) z – Guard cells. They swell when water flows into them, causing the stomatal pores to open. 37. The electric current and magnetic field are used in electric motor, electric generator, loud speaker, microphone and in measuring devices. Section C 38. ( a ) N2(g) + 3H2(g)  2NH3(g) Nitrogen Hydrogen Ammonia ( b ) 2H2S(g) + 3O2(g)  2SO2(g) + 2H2O(l) Hydrogen Oxygen Sulphur Water Sulphide dioxide ( c ) 2K(s) + 2H2O(l)  2KOH(aq) + H2(g) Pota- water Potassium Hydrogen ssium hydroxide 39. ( 1 ) Minerals : The elements or compounds, which occur naturally in the earth’s crust are known as minerals. ( 2 ) Ores : The minerals which contain a very high percentage of a particular metal and it can be extracted profitably from them are called ores. ( 3 ) Gangue : Ores obtained from the earth’s crust does not contain ores of elements only, but ores are usually contaminated with large amount of impurities such as soil, sand, compounds of other metals, etc. These impurities are called gangue.