146. Choose and write the correct alternative : What happens when dilute hydrochloric acid is added to iron filling? (a) Hydrogen gas 2022 147. Fill in the blanks : (i) Newlands gave the law of _______. (ii) Fishes have only ______ chambers in their heart. 2022 148. Match the column : (i) Formula of common salt (a) Oersted (ii) Non-metal lodine (b) NaCl 2022 149. Write the answers in one sentence each : (i) Write the pH value of acidic solution. (ii) What is the homogenous mixture of two or 2022 150. Why do we apply paint on icon articles ? 2022 151. Why is respiration considered an exothermic reaction ? 2022 152. Write two ways of prevention of corrosion. 2022 153. Write two differences between metal and non-metal. 2022 154. Define the atomic size. 2022 155. Write two limitations of Newland's Law of Octaves. 2022 156. What would be the consequences of deficiency of Hemoglobin in our body. 2022 157. What is autotrophic nutrition ? 2022 158. Why is reproduction essential ? 2022 159. Define the unisexual flower. 2022 160. Why did Mendel choosen the pea plant for their experiment ? Write any two reasons. 2022 161. What is heredity ? 2022 162. Write the laws of reflection of light. 2022 163. Define the magnification. 2022 164. On what factors does the resistance of a conductor depend ? Write any two factors. 2022 165. How much work is done in moving a charge of 2 C across two points having a potential difference 12 V ? 2022 166. Draw any two symbols of the components used in electric circuit. 2022 167. Why is the tungsten used almost exclusively for filament of electric lamps ? 2022 168. Give any two ways in which non-biodegradable substances would affect the environment. 2022 169. What is ecosystem ? 2022 170. Define the Combination reaction and Decomposition reaction. 2022 171. Why should a magnesium ribbon be cleaned before burning in air ? 2022 172. Draw a labelled diagram of the human eye. 2022 173. Draw a labelled diagram of dispersion of white light by the glass prism. 2022 174. Write any three properties of magnetic field lines. 2022 175. What is Right-hand thumb rule ? Write. 2022 176. What. are the advantages of using a solar cooker ? (any four) 2022 177. What are the qualities of an ideal source of energy ? 2022 178. Write any four differences between acid and base. 2022 179. Write any four uses of Plaster of Paris. 2022 180. Write the differences between soap and detergents. (any four) 2022 181. Draw the electron dot structure of methane (CH4) and ethene (C2H4). 2022 182. Write the differences between xylem and phloem. (any four) 2022 183. Write the differences between blood and lymph. 2022 184. Write any two uses of concave mirrors. 2022 185. Find the focal length of a convex mirror whose radius of curvature is 32 cm. 2022 186. What is converging lens ? 2022 187. The radius of curvature of a spherical mirror is 20 cm. What will be its focal length ? 2022