CBSE ADDA

QUESTIONS FROM CBSE EXAMINATION PAPERS I. VERY SHORT ANSWER QUESTIONS (1 Mark) 1. Why do silver ornaments loose their shine when kept for some time? [2010 (T-1)] 2. Name a metal other than aluminium that is covered with an oxide film layer. [2010 (T-1)] 3. Name one metal and one non-metal which exists in liquid state at room temperature? [2010 (T-1)] 4. Name a non-metal which is lustrous and a metal which is non-lustrous. [2010 (T-1)] 5. Name two metals which have very low melting point. [2010 (T-1)] 6. If copper metal is heated over a flame, it develops a coating. What is the colour and composition of this coating? [2010 (T-1)] 7. Why is sodium metal kept immersed in kerosene oil? [2010 (T-1)] 8. Name one metal which react with very dilute HNO3 to evolve hydrogen gas. [2010 (T-1)] 9. A non-metal X exists in two different forms Y and Z. Y is the hardest natural substance, whereas Z is a good conductor of electricity. Identify X, Y, and Z. [2010 (T-1)] 10. An element A form

Q.1 Define matter. Ans: Anything that occupies space and has mass and is felt by senses is called matter. Q.2 what happens if you put copper sulphate crystals in water? Ans: Copper sulphate crystals mixed between the spaces of molecules of water and disappear. Q.3 A substance has a definite volume but no definite shape? State whether this substance is a solid, a liquid or a gas. Ans: Liguid Q.4 Arrange the following substances in increasing order of force of attraction between the particles.  (a) Milk (b) Salt (c) Oxygen. Ans: Oxygen < Milk< Salt Q.5 A substance has neither a fixed shape nor a fixed volume . State whether it is a solid , a liquid or a gas. Ans: Gas Q.6 The melting point of a substance is below the room temperature. Predict its physical state. Ans: Ice Q.7 What is vapour ? Ans: A substance that found in gaseous state only at room temperature is called Vapour Q.8 Name the temperature at which the solid and liquid state