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

1. Why do mountaineer carry oxygen cylinder while climbing? Ans: This is because amount of oxygen at high altitude and become difficult to breadth. 2.  Why does smell of perfumes reach us several meters away? Ans: This is because air is continuously moving it takes the particle of perfumes along with it. 3. Why does crocodile keep it snout out of the water while resting? Ans: Crocodile keeps it snout out of the water while resting to breathe through nostril. 4. Why do we see bubbles in water before it starts boiling? Ans: This is because dissolved air is expelled out o heating. 5. Why do animals that live in holes or borrow in soil breadth? Ans: They breadth in oxygen present between the soil partials. 6. What is the role of air in water cycle? Ans: Air helps the water vapour to rise up to form cloud. 7. What does air bubbles coming out of soil, when pt in water indicates? Ans: The presence of air 8. Why long chimneys are installed in factories?

CBSE 6 th Chapter -Waste  (Garbage In, Garbage Out ) • Introduction • Segregation of wastes • Management of biodegradable wastes • Composting, Landfills - Structure of a landfill • Management of Non-Biodegradable Wastes • Reduce, Reuse, Recycle - Recycling of Plastics,  Recycling of paper Garbage Disposal A large, low-lying area used to dispose garbage is known  as a dump.  A garbage dump is also used as landfill. Garbage collectors collect waste and then dispose it at  garbage disposals.  Garbage dumps have flies, cockroaches and mosquitoes, and later turn into breeding  grounds for micro-organisms that may cause diseases. That is why these garbage dumps are usually located  on the outskirts of a city. Components of garbage: Garbage has useful and non-useful components. ü   Useful garbage components are those that can be decayed easily. The process of decaying is known as  composting. Useful garbage components are fruit and vegetable waste, pl

(I) answer the following questions in one word 1. What is the age of puberty in girl? Ans: 10 – 12 years 2. Which gland secretes Corticoid hormones? Ans: Adrenal Glands 3. What types of fertilization takes place in Man? Ans: Internal Fertilization 4. What is the other name of Endocrine garland? Ans; Ductless gland 5. What is the term used for development of Ovum without fertilization? Ans: Parthenogenesis 6. Name the hormones secreted by pineal glands? Ans: Melatonin 7. Which gland is called master glands? Ans: Pituitary Gland 8. When chromosome is not sex chromosomes, what is it called? Ans: autosomes 9. Name the term used for having X and Y chromosomes. Ans: Sperm gamete 10. Name the hormones secreted by testes? Ans: Testosterone (II) Answer the following questions in brief 1. Why does our body changes when we reach to teens? Ans: when we reach to teens, Endocrine system of or body regulate the release of hormo