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UNIFIED COUNCIL A n I S O 9 0 0 1 : 2008 C e r t i f i e d O r g a n i s a t i o n Test Assess Achieve NATIONAL LEVEL SCIENCE TALENT SEARCH EXAMINATION Solutions for Class : 7 MATHEMATICS Therefore, ABF EDF. 1. (B) A= a = 50° PHYSICS a+ c = 180° 6. (A) When the end M of a metal rod given in the figure is heated the drop w placed at c = 130° 5 cm takes 2 minutes to fall off. Hence, b= c = 130° for a drop at 10 cm to fall off, it takes 2 × 2 = 4 minutes. 2. (D) DEF = 180° – 124° = 56° Thus, the time taken by drops x, y, z are DCE = DEC = 56° [ DC = DE] 4 minutes, 6 minutes and 10 minutes But BCA + 72° +56° = 180° respectively. BCA = 52° 7. (B) Electrical appliances shown in options (A), (C) and (D) use the magnetic effects A= BCA = 52° of current. An electric bulb converts the In ABC, 52° + 52° + y = 180° electric energy to light energy. y = 76° 8. (D) As per the image of a clock as seen in a plane mirror, the correct time is 9.25. 3. (A) PQR is equilateral. 9. (B) A hot air balloon rises up because the Each of its angles is 60. hot air in the balloon is less dense than In PRS, PR = RS the cooler air surrounding it. x + y + y = 180° 10. (C) Conduction occurs only in solids, Also, x = 180° – 60° = 120° convection occurs only in liquids and gases, and radiation requires no 180° 120° medium. y= = 30° 2 CHEMISTRY 4. (C) In PRS, given PR = RS 11. (C) A glass bottle after it breaks undergoes S= RPS = 28° a change only in its size and shape, but not in its composition. So, it is a physical QPS = 90° + 28° = 118° change. In PQS x + 118° + 28° = 180° 12. (C) Air on the surface of the earth gets x + 146° = 180° heated up due to sunlight. It becomes lighter and goes up. It gets cooled and x = 34° comes down. Thus, convectional currents 5. (A) When considering congruent triangles, occur on the earth. the order is very important. website : www.unifiedcouncil.com 1
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13. (A) Statements I and II are correct. 20. (A) P-Respiration; Q-Photosynthesis; (I) Ozone protects us from sun’s R-Respiration. harmful radiations. CRITICAL THINKING (II) Ozone absorbs the UV radiations 21. (C) from the sun and breaks down to oxygen. 22. (A) (III) Ozone acts as a protective shield 23. (D) not oxygen. 24. (C) 14. (A) Sodium hydroxide and hydrochloric acid 25. (B) react to form sodium chloride and water which is a neutralisation reaction. Option (B): It is a thermal decomposition of calcium carbonate. Option (C): It is the burning (combustion) of hydrogen gas. Option (D): It is the burning (combustion) of methane gas. 15. (C) Water is first allowed to settle so that a sediment of impurities is formed. Then chemicals like alum and lime are added so that sediments further settle down. Then the water is filtered through sand and gravel, there by making it pure. Then it is chlorinated to make it free from germs and bacteria. BIOLOGY 16. (D) Pitcher plant / venus fly trap / bladder wort. Pitcher plant found in Khassia hills of Meghalaya is an endangered plant producing pitchers as modified leaf lamina. They attract and kill their prey, but passively through their attractive colours. They also produce sugary nectar and sweet scents. From this relationship the plants primarily gain nitrogen and phosphorous to supplement there nutrient requirement for growth. 17. (A) Oesophagus connect the mouth to the stomach. 18. (D) – Malphigian tubules. 19. (B) C E B D A website : www.unifiedcouncil.com 2
