Page 1 :
STD : VIIIth, SUBJECT : SCIENCE, , MAJOR TEST, DATE : 10-01-2022, , MARKS : 50, TIME : 2 hr, , ( 12. Introduction to Acid and Base, 13. Chemical Change and Chemical, Bond, 16. Reflection of Light), , (Q.I) Choose the correct alternative., (3m), 1) To soften hard water, a solution of _______ is added., (a) Washing soda, (b) Alum, (c) Bleaching powder, (d) Baking soda, 2) In tomato _______ is present., (a) citric acid, (b) tartaric acid, (c) oxalic acid, (d) acetic acid, 3) If angle between incident ray and surface is 27°, the angle, between normal and reflected ray is _____., (a) 27°, (b) 90°, (c) 63°, (d) 127°, (Q.II.A) Fill in the blanks., (2m), 1) Oxygen is a ________ in respiration., 2) The reflection of light from a wooden surface is _______, reflection., (B) Match the following., Group A, , (2m), Group B, , 1. Weak acid, , a. Covalent bond, , 2. Strong acid, , b. Ionic bond, , 3. H2O, , c., , 4. NaCl, , d. Carbonic acid (H2CO3), , Nitric acid (HNO3), , 1
Page 2 :
(C) Write whether True or False; if False write correct statement., (2m), 1) Acid reacts with carbonates to liberate CO2 gas., 2) Laws of reflection are followed only by regular reflection., (D) Name the following., (2m), 1) Organic acid that forms part of our body., 2) An instrument that works on the principle of reflection of, light., (E) Write chemical names from given formulae., 1) NH4OH, 2) Mg(OH)2, 3) KOH, 4) NaHCO3, , (2m), , (F) Define., 1) Normal, , (2m), 2) Base, , (Q.III) Answer any 5 out of 6., (10m), 1) Show with the help of diagram of electronic configuration, how WATER is formed from the constituent atoms., 2) Enlist any 2 properties each of acid and base., 3) Draw a figure showing the following., (i)Normal, (ii) Angle of incidence, (iii) Angle of reflection, (iv) Point of incidence, 4) Which acid is used for getting chloride salt?, 5) Distinguish between regular and irregular reflection of light., 6) Why we cannot see the objects in a dark room?, 2
Page 3 :
(Q.IV) Answer any 5 out of 6., (15m), 1) Write a note on indicator., 2) Explain by writing a word equation., Lime stone powder disappears on adding to dilute, hydrochloric acid., 3) The label on the bottle of chemical is spoiled. How will you, find whether the chemical is acidic or basic?, 4) Draw a neat labelled diagram of Periscope., 5) Which are the industrial uses of acids?, 6) Classify following substances into acidic, basic and neutral, group - NaCl, MgO, KCl, Hâ‚‚SO, HNO3, Naâ‚‚CO3., (Q.V) Answer any 2 out of 3., (10m), 1) a. Give the different uses of acid and alkali (4 uses each), b. Why indicator does not get affected by salt?, 2) a. Define ionic and covalent bond., b. Give examples of compounds formed by ionic and covalent, bond. (2 e.g. each)., c. Why do noble gases not form any chemical bond?, 3) a. Study the following incident, Swara and Yash were looking in a water filled vessel. They, could see their images clearly in the still water. At that, instant, Yash threw a stone in the water. Now their images, were blurred. Swara could not understand the reason for, the blurring of the images., Explain the reason for blurring of the images to Swara by, answering the following questions., (i) Is there a relation between the reflection of light and the, blurring of the images?, (ii) Which types of reflection of light can you notice from, this?, , 3
Page 4 :
(iii) Are laws of reflection followed in these types of, reflection?, b. If the angle between the incident ray and the reflected ray, is 100°; what are the values of the angle of incidence and, angle of reflection?, , *****, , 《All the Best》, , 4
