NSTSE Sample Paper Solutions Class 8

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 : 8 MATHEMATICS ab a b 4. (C)   1. (C)  BDC =  AED = 36° c c c (Corresponding  s, AE  BD.) 5. (C) By folding the given net, the cube in  ABD =  BDC = 36° option (C) can be formed. (Alternate  s, AB  DC) PHYSICS  ADB =  ABD = 36° 6. (D) As per the laws of reflection of light i (Base angles of isoceles  , since AB = DC) = r . The angle of reflection is 70o, as the angle of incidence is 70o.  BAD = 180o –  ABD –  ADB 7. (D) In mercury barometers, the atmosphere (Angle sum of a triangle.) (or the air) pushes down on the mercury = 180° – 36° – 36° in the trough. This in turn pushes the mercury in the tube up. The height of = 108° mercury in the tube is used as a 2. (B) Area of shaded region = 15  8cm2 – measure of atmospheric pressure. So, 1 higher the level of mercury in the tube  12  8cm2 irrespective of the shape of the tube, 2 higher is the atmospheric air pressure. = 120 cm2 – 48 cm2 The highest level of the mercury inside = 72 cm2 the barometer indicates the highest air pressure. 3. (B) Since x and y are directly proportional, we have 8. (B) We know that for a reflected ray, the angle that the incident ray makes with 3 x 1 x  1   1 the line perpendicular to the surface is 30 50 10 50 equal to the angle made by the reflected  1  ray with this perpendicular line. N is the  x1    50   5  10  correct reflected ray of X. 3 x 1 x  2   2 9. (D) The air rushed out of the balloon and 30 80 10 80 pushed the set-up forward in direction  1   x 2    80   8 Y. Frictional force acts in the opposite  10  direction of motion, i.e., Z. 3 10 1 10 10. (A) First, compare P and Q. The distance    30 y 1 10 y 1 moved is the same (130 cm), so the  (y 1  1)  (10  10)  y 1  100 one with the higher magnitude will move faster. It is P. Next, compare R  x1  5, x 2  8 and y 1  100 website : www.unifiedcouncil.com 1

and S. The distance moved is 90 cm. The BIOLOGY one that moved that distance in the 16. (B) Agriculture is the cultivation and shorter amount of time has the larger breeding of animals, plants and fungi for magnitude. It is R. Finally, compare P food, fiber, biofuel and other products and R. They both took 7 seconds to used to sustain and enhance human life. complete. Therefore, if we look at the distance moved, the one that 17. (B) Echinodermates include starfish, sea completed the longer distance in 7 urchins and brittle stars. They mostly seconds has the higher magnitude have fivefold symmetry with spiny outer covering. CHEMISTRY 18. (C) Mucor reproduces by spores. 11. (D) Coal when burnt releases sulphur dioxide and smoke that pollutes the air. 19. (B) ‘P’ is binary fission and ‘Q’ is budding. Binary fission and loudding are a sexual 12. (A) Metal P reacts both with water and repreoduction. dilute hydrochloric acid. Metal Q does 20. (C) Organelle chloroplast converts light not react with water but reacts with energy to chemical energy during the dilute hydrochloric acid. Metal R does process of photosynthesis. It has not react with water and dilute chlorophyll to trap sunlight during hydrochloric acid. P, Q, R is the correct photosynthesis.n reactivity in a decreasing order of given metals. CRITICAL THINKING 13. (D) For fires involving inflammable materials 21. (C) like petrol and electrical equipment 22. (B) carbon dioxide (CO 2 ) is the best extinguisher. CO2, being heavier than 23. (B) oxygen, covers the fire like a blanket. As 24. (A) the contact between the fuel and oxygen is cut off, the fire is controlled. The 25. (D) added advantage of CO2 is that in most of the cases it does not harm the electrical equipment. 14. (A) Copper being more reactive than silver, displaces silver and the solution turns blue due to the formation of copper nitrate. 15. (D) The correct matching is : a – 4, b – 1, c – 2, d – 3 (i) Silk - Saree (ii) Nylon - Rope (iii) Acrylic - Sweater (iv) Plastic - Bottle website : www.unifiedcouncil.com 2