Questions 1 to 4 are one mark questions. These are to be answered in one word or one sentence. Section A 1. State the chemical change that takes place when lime stone is heated strongly. 2. .Why do silver articles become black after some time when exposed to air ? 3. Name the device which directly converts solar energy into electrical energy. 4. What are amphoteric oxides ? Choose the amphoteric oxides amongst the following oxides. Na 2 O, ZnO, Al 2 O 3 , CO 2 , H 2 O Questions 5 to 13 are two marks questions. These are to be answered in about 30 words each. 5. Draw circuit symbols of the following components : (i) Variable resistance or rheostat (ii) Plug key or switch (closed) 6. What are antacids ? Name two compounds which are used as antacids. 7. A small amount of ferrous sulphate crystals were heated in a hard glass test tube ? (i) Write the equati
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