Is Master Around Us Pure (Solved)
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Q. 91. Explain with reason that burning of oil is a chemical change.
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Q.92. Explain how change in energy takes place in both physical and chemical change.
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Q.93. Distinguish between physical and chemical change.
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Q. 94. Write some examples of physical change and some examples of chemical change.
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Q. 95. Classify as a physical or chemical change, the following :
(i) Cutting of rod,
(ii) melting of coconut oil,
(iii) rusting of iron,
(iv) turning steam from water,
(v) breaking of water into hydrogen and oxygen,
(vi) diluting acid.
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Q.96. Give examples of some physical change and explain it.
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Q. 97. Give some examples of chemical change and explain it.
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Q. 98. Melting of wax is a physical change but burning of candle is a chemical change. Why ?
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Q.99. Classify the following as a physical or chemical changes :
Cutting of trees, melting of butter in a pan , rusting of almirah, boiling of water to form steam, passing an electric current through water and water breaking down into hydrogen and oxygen gases, dissolving of common salt in water, making a fruit saladwith raw fruits and burning of paper and wood.
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Q. 100. Try segregating the things around you as pure substances or mixtures.
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Q. 101. What is element ?
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Q. 102. What happens when red mercuric oxide is heated ?
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Q. 103. A substance that can not be decomposed under ordinary circumstances either by physical or by chemical process. Name it.
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Q. 104. What is compound. Give examples.
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Q.105. Differentiate between an element and a compound.
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Q. 106. Classify each of the following as element, compound or mixture :
sugar, milk, diamond, iron, phosphorus, brass, air, water, urea, oxygen, carbon dioxide, glucose, bronze.
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Q.107. State in which of the following process, compound is formed :
(i) dilution of acid,
(ii) mixing sand and chalk,
(iii) crushing sulphur and iron filings,
(iv) burning of magnesium in air.
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Q. 108. Select the true statement from the following :-
(i) Air is compound,
(ii) Blood is a compound,
(iii) Mercury is an element,
(iv) Milk is a homogeneous mixture.
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Q.109. Give some examples of element, mixture and compound.
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Q.110. Why hydrogen is called an element ?
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Q.111. Water is a compound. Why ?
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Q.112. Name some gaseous elements, liquid elements and solid elements.
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Q. 113. Name the elements present in the following compounds :
(i) Sodium Sulphate,
(ii) Nitric Acid and
(iii) Potassium Nitrate.
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Q.114. A pure substance on heating leaves behind a white residue and gives out a colourless, odourless gas. Can you say that the given substance is an element, compound or mixture.
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Q. 115. Guess the material which shows the following properties :
(i) Average properties of constituents contained in it.
(ii) Components has a fixed ratio.
(iii) Not converted into more simpler form by ordinary chemical method.
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Q.116. Choose the elements from the following substances giving reason :
(i) Diamond
(ii) Graphite
(iii) Soda water
(iv) Stainless steel
(v) common salt
(vi) Iron filings
(vii) Copper wire.
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Q. 117. Which of the following are elements :
Water, Milk, Sulphur, Smoke, Manganese, Coke and Glucose.
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Q. 118. Write physical properties of metals
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Q. 119. Write physical properties of non-metals.
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Q. 120. What are metalloid. Explain with suitable examples.
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