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. Na2O, ZnO, Al2O3, CO2, H2O
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 equations involved in the above reaction (ii) Name the type of reaction that takes/ place ?
8. A white salt on heating decomposes to give brown fumes and a residue is left behind. (i) Name the salt. (ii) Write the equation for the decomposition reaction.
9. Out of two solar cookers one was covered by a plane glass slab and the other was left open. Which of two solar cookers will be more efficient and why ?
10. A wire of resistance R is cut into three equal parts. (i) Find the value of resistance of each part in terms of the original resistance R ? (ii) If these three pieces are connected in parallel, what is the ratio of the equivalent resistance so obtained with the original resistance ?
11. How does the strength of the Magnetic field at the center of a circular coil of a wire depend on : (a) radius of the coil (b) number of turns in the coil
12. State Ohm’s law and write the condition in which this law is obeyed ?
13. (a) What happens when quick lime is added to water ? (b) Write chemical equation for the above reaction. (c) Which type of reaction is this?
Questions 14 to 22 are three marks questions. These are to be answered in about 50 words each
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