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5. Read the following and answer any four questions from (i) to (v) Oxidation has damaging effect on metals as well as on food. The damaging effect of oxidation on metal is studied as corrosion and that on food is studied as rancidity. The phenomenon due to which metals are slowly eaten away by the reaction of air, water and chemicals present in atmosphere, is called corrosion. For example, iron articles are shiny when new, but get coated with a reddish brown powder when left for sometime. This process is known as rusting of iron. Rancidity is the process of slow oxidation of oil and fat (which are volatile in nature) present in the food materials resulting in the change of smell and taste in them.
(i) Rancidity can be prevented by (a) adding antioxidants (b) packaging oily food in nitrogen gas (c) both (a) and (b) (d) none of these. Ans: (c) both (a) and (b) (ii) Combination of phosphorus and oxygen is an example ...
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Read the following and answer any four questions from (i) to (v) Whenever a solution has a pH of less than 7, it will be an acidic solution. For example, a solution having a Ph of 4 will be acidic in nature (or it will be an acid). Please note that more acidic a solution is, the lower will be its pH. For example, a solution of pH 1 is much more acidic than another solution of pH 4. In other words, a solution of pH 1 will be a much more stronger acid than another acidhaving pH 4 (see the figure). The solutions having pH of 0, 1, 2 and 3 are usually considered to be strong acids. And the solutions having pH of 4, 5 and 6 are considered to be weak acid solutions. It is clear that the acidity of a substance is related to its pH. Strongly acidic substances have a very low pH. In fact, lower the pH, the stronger the acid.
(i) A solution turns red litmus blue. Its pH is likely to be : (a) 1 (b) 4 (c) 5 (d) 10 Ans: (d) 10 (ii) The pH values of six solutions A to F are given below : A ...
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3. Read the following and answer any four questions from (i) to (v) A group of students measured the pH of some substances they found in their homes. Their results are given in the following table
(a) Which solution is the most acidic? (i) Apples (ii) Vinegar (iii) Lemon Juice (iv) Black Coffee Ans: (iii) Lemon juice (b) Which solution is the most alkaline ? (i) Household ammonia (ii) Washing soda (iii) Baking soda (iv) Toothpaste
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. Read the following and answer any four questions from (i) to (v) A girl met with an accident and his leg fractured. She went to orthopedics doctor for treatment. On examination, the doctor mixed the white power in water and applied to her leg along with the cotton and gauze. After a while, it turned into white, solid, hard mass. He said that it would support her fractured bone in the right position.
(1) After treatment, the doctor repacked the white powder back into moisture proof, airtight container. Why? (a) The fungus growth will occur in open (b) The powder would react to moisture and turn into solid mass (c) The powder with ...
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. Read the following and answer any four questions from (i) to (v) A girl met with an accident and his leg fractured. She went to orthopedics doctor for treatment. On examination, the doctor mixed the white power in water and applied to her leg along with the cotton and gauze. After a while, it turned into white, solid, hard mass. He said that it would support her fractured bone in the right position.
(1) After treatment, the doctor repacked the white powder back into moisture proof, airtight container. Why? (a) The fungus growth will occur in open (b) The powder would react to moisture and turn into solid mass (c) The powder with ...
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3 years 0 Answers 20 views Enlightened 0

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(i) The difference of water molecules in gypsum and plaster of Paris is (a) 5/2 (b) 2 (c) 1/2 d) 3/2 (ii) Plaster of Paris hardens by (a) giving off CO2 b) changing into CaCO2 (c) combining with water d) giving ...
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