Model Activity Sheet Solution (Science and Technology - Part 1)

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2 Model Activity Sheet Solution (Science and Technology - Part 1) Note: Answer to every question must be written on a new page. Q.1. (A) i. When objects of equal masses at specific temperature are supplied with equal heat, their final temperature is observed to be different. This is due to difference in their specific heat capacities. ii. iii. Wrong The process of coating zinc over iron or steel is called galvanization. Cobalt Cobalt is a d-block element while others are p-block elements. iv. F = x 4 GmAmB Hint: F 1 = d and F = Gm m A B d F1 = 4 = x 4 Q.1. v. PSLV Indian National Satellite (INSAT) is launched using a GSLV (Geosynchronous Satellite Launch Vehicle). Similarly, Indian Regional Navigation Satellite System (IRNSS) is launched using a PSLV (Polar Satellite Launch Vehicle). (B) i. Combination reaction is Mg + O MgO. ii. iii. iv. A person weighing 100 N on the pole will weigh less on the equator. Hint: As value of gravitational acceleration decreases from pole to equator, weight of the person will decrease as he moves from the pole to equator. A bulb of power 60 W when connected across potential difference of 0 V will draw current of 0.7 A. Hint: I = P V = 60 0 = 0.7 A When ethanol reacts with sodium, the gas evolved burns with pop sound. v. When a ray of light passes through glass slab, refraction of light occurs twice. Q.. i. a. White precipitate of silver chloride (AgCl) is formed. The type of chemical reaction is double displacement reaction. b. Chemical equation: AgNO 3(aq) + NaCl (aq) AgCl + NaNO 3(aq) Silver Sodium Silver chloride Sodium nitrate chloride (precipitate) nitrate ii. Solution: Given: Speed of light in medium (v ) = m/s To find: Absolute refractive index (n) v1 Formula: n = v Calculation: From formula, n =. ( velocity of light in vacuum = m/s) = 1.33 Ans: The absolute refractive index of the medium is

3 IQB iii. When zinc is treated with dilute hydrochloric acid, zinc chloride is formed with the evolution of hydrogen gas. Zn (s) + HCl (aq) ZnCl (aq) + H Zinc Hydrochloric acid Zinc chloride Hydrogen Q.3. i. iv. (a): Position of the object: At F 1 (b): Position of the image: At F (c): Position of the image: On the same side of the lens as the object (d): Nature of the image: Virtual and erect v. a. First member of homologous series of amines is, H H H C N H H (Methnamine) b. Third member of homologous series of carboxylic acids is, H H O H C C C O H H H (Propanoic acid) vi. a. Structural formula of polyvinyl chloride (PVC) is, H H C C H Cl n b. Uses: Polyvinyl chloride (PVC) is used in pipes, door mats, tubes and bags in hospital kits vii. a. Fuel in the launch vehicle forms the major part of the total weight of the launch vehicle. b. Thus, the vehicle has to carry large amount of weight in the form of fuel with it. c. For the launch vehicles with more than one stage, the fuel in the first stage is used to give the initial thrust to the vehicle. After this fuel is exhausted, the empty fuel tank along with the engine is detached from the main body of the vehicle. This reduces weight of the vehicle step by step. Hence, it is beneficial to use satellite launch vehicles made of more than one stage. Incident ray P S i N r Refracted ray r M Medium 1 (n 1 ) Medium (n ) e Q R Glass slab Emergent ray a. In the figure given above, refraction of light takes place twice in the glass slab. The first refraction takes place at point N on side PQ when the ray of light enters from air medium to glass medium.

4 Model Activity Sheet Solution b. The second refraction takes place at M on side SR when the ray of light enters from glass medium to air medium. c. In the above figure, i = angle of incidence, r = angle of refraction, e = angle of emergence. At point N, using Snell s law, airn glass = sini.(1) sin r At point M, using Snell s law glassn air = sin r.() sin e 1 But air n glass = n sini 1 sin r sin r sine sin i sin e sinr sinr glass air.[from (1) and ()] sin i = sin e i = e d. Hence, for the refraction of light through a glass slab angle of incidence is equal to angle of emergence, i.e., i = e. ii. a. The description given works on the principle of heat exchange. b. Q z denotes heat gained by water in the calorimeter and Q x denotes heat lost by gold object. c. Specific heat is a property of a substance and is different for different substances. Hence, specific heat of silver object will be different than specific heat of gold object. iii. a. According to Newton s law of gravitation, Gm1m F = r G = Fr mm 1.(1) b. In SI system, force is measured in newton (N), distance is measured in metre (m) and mass is measured in kilogram (kg). c. newton (metre) Substituting in equation (1), we get, unit of G as, kg kg d. Thus, in SI system, Nm Unit of G = kg or newton m kg e. The value of G in SI units would equal to the gravitational force between two masses of 1 kg when these masses are kept apart by distance of 1 m. iv. a. From the given experiment, displacement reaction is studied. b. In test tube A, the blue colour of the solution will turn to green and copper coating will form on iron rail. No reaction will take place in test tube B. c. Fe (s) + CuSO 4(aq) FeSO 4(aq) + Cu (s) Iron Copper Ferrous Copper sulphate sulphate v. a. The type of lens used in Shruti s spectacle is concave lens with negative power. b. Shruti is suffering from myopia or nearsightedness. c. Solution: Given: Power of lens (P) = 3.0 D. To find: Focal length (f ) 3

5 IQB Formula: P = 1 f Calculation: From Formula, f = 1 P = 1 = 0.3 m = 30 cm 3 Ans: Focal length of the lenses used in Shruti s spectacles is 30 cm. vi. a. Thistle funnel Stand Delivery tube Test tube Ethanoic acid Test tube Lime water Sodium carbonate b. The gas evolved in the above experiment is carbon dioxide, CO. It turns lime water milky. The chemical equation is Ca(OH) (aq) + CO (g) CaCO 3(s) + H O (l) Calcium hydroxide (Lime water) Carbon dioxide Calcium carbonate (Turns lime water milky) Water c. The chemical equation for the reaction between ethanoic acid and sodium carbonate is as follows: CH 3 COOH (aq) + Na CO 3(s) CH 3 COONa (aq) + H O (l) + CO Ethanoic acid Sodium carbonate Sodium ethanoate Water Carbon dioxide vii. a. 3Cu (s) + 8HNO 3(aq) Copper Dilute nitric acid 3Cu(NO 3 ) (aq) + NO + 4H O (l) Copper (II) nitrate Nitric oxide Water b. C 1 H O 11(s) 1C (s) + 11H O (g) Sugar Carbon Water vapour 4 c. CuSO 4(aq) + Zn (s) ZnSO 4(aq) + Cu (s) Copper Zinc Zinc Copper sulphate sulphate Q.4. i. a. The device mentioned is DC electric generator. b. DC generator works on the principle of electromagnetic induction, i.e., when the coil rotates in a magnetic field, the magnetic field induces a current in this coil. The induced current then flows into the circuit connected to the coil. c. The main components of DC generator are: Rectangular coil (ABCD), strong magnets, split ring, carbon brushes and axle.

6 d. Schematic representation: Coil Model Activity Sheet Solution N S Split ring Axle A Carbon brushes e. If instead of split ring, conducting ring is used then, it is possible to obtain alternating current by modifying construction of DC electric generator. ii. a. In the modern periodic table, elements are arranged on the basis of their atomic numbers. b. Element B is a metalloid. The name of the element is boron (B). c. Element A is a metal while elements C, D and E are nonmetals. d. Element E has the smallest atomic size because atomic size decreases while going from left to right in a period. e. The electronic configuration of A is (, ) and the electronic configuration of E is (, 6). 5

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