Page 1 :
Circle the odd ones. Give reasons for your choice., , 1. Reforestation — It is not a type of pollution, whereas others are the, types of pollution., , 2. Dust particles — This is not a gas, these are impurities, whereas the, others are gases., , Fill in the blanks., , 1. atmosphere 2. wind 3. mixture 4. oxygen 5. carbon dioxide, , SECTION B, , Multiple Choice Questions (MCQs) Scientific/Practical skills., , 1. (b) 2. (d) 3. (b), , Very Short Answer Questions., , 1. Oxygen 2. around 300 km, , 3. Oxygen, nitrogen, carbon dioxide, noble gases and water vapour, , 4. (i) Oxygen is a colourless, odourless and tasteless gas., , (ii) Oxygen is soluble in water., , 5. Oxygen, , 6. When we add water to the soil, the air bubbles come out. Bubbles, appear because water pushes the trapped air out of the spaces between, the particles of soil., , 7. Oxygen, , Short Answer Questions., , 1. (a) More water vapour, (b) Increased level of dust, smoke and gases especially higher amount, , of carbon dioxide and oxides of nitrogen and sulphur., , 2. The blanket of air that surrounds the Earth is called atmosphere. The, major components of air are nitrogen, oxygen, carbon dioxide and a few, other gases, water vapour, smoke and dust particles., , 3. (a) The doctor provides extra oxygen to Priyanka’s uncle by an oxygen, , cylinder., (b) Care for others and taking quick decisions in case of emergency or, critical situation., , 4. Nitrogen is needed by living organisms as it forms various components, of the body of living organisms like proteins and nucleic acids., , 5. Air contains oxygen. If there is no air in water then aquatic plants will die, due to the absence of oxygen., , 6. Air helps in maintaining proper temperature on the Earth. During the, day, when the Sun rays fall on the Earth, some of them get absorbed, by the atmosphere and rest are reflected back. This trapped heat, prevents Earth’s atmosphere from too much cooling at night and helps, to maintain appropriate temperature.