Let abc be a three-digit number. Then abc – cba is not divisible by (a) 9 (b) 11 (c) 18 (d) 33
Answer: (c) 18 General representation of a number The general representation of a number is as follows: For a two-digit... View Article
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The usual form of 1000a + 10b + c is (a) abc (b) abco (c) aobc (d) aboc
Answer: (c) a0bc The usual form to represent the aobc is 1000 x a + 100 x 0 + 10... View Article
Generalised form of a two-digit number xy is (a) x + y (b) 10x + y (c) 10x – y (d) 10y + x
Answer: (b) 10x + y The numbers are expressed as the sum of the product of it digits with the... View Article
Generalised form of a four-digit number abdc is (a) 1000 a + 100 b + 10 c + d (b) 1000 a + 100 c + 10 b + d (c) 1000 a + 100 b + 10 d + c (d) a × b × c × d
Answer: (c) 1000 a + 100 b + 10 d + c We know that, the numbers are expressed as... View Article
A mixture of iron nails, salt, oil and water is provided to you. Give stepwise methods to separate each component from this mixture.
Answer: A mixture of iron nails, salt, oil and water can be separated by the following steps: Iron nails can... View Article
You are provided with a mixture of salt, sand, oil and water. Write the steps involved for the separation of salt, sand and oil from the mixture by giving an activity along with the diagram.
Answer: A mixture of salt, sand, oil and water can be separated by using these steps: 1. Decant the oil... View Article
Read the story titled “WISE FARMER” and tick the correct option to complete the story. A farmer was sad/happy to see his healthy wheat crop ready for harvest. He harvested the crops and left it under the sun/rain to dry the stalks. To separate the seeds from the bundles of the stalk he handpicked/threshed them. After gathering the seed grains he wanted to separate the stones and husk from it. His wife winnowed/threshed them to separate the husk and later sieved/handpicked to remove stones from it. She ground the wheat grains and sieved/filtered the flour. The wise farmer and his wife got a good price for the flour. Can you tell why?
Answer: (i) Happy (ii) Sun (iii) Threshed (iv) Winnowed (v) Handpicked (vi) Sieved A farmer was happy to see his... View Article
Paheli was feeling thirsty but there was only a pot of water at home which was muddy and unfit for drinking. How do you think Paheli would have made this water fit for drinking if the following materials were available to her. [Alum, tub, muslin cloth, gas stove, thread, pan and lid.]
Answer: With the following materials available: alum, tub, muslin cloth, gas stove, thread, pan and lid Paheli could undertake the... View Article
Both Sarika and Mohan were asked to make a salt solution. Sarika was given a teaspoonful of salt and half a glass of water, whereas Mohan was given twenty teaspoons full of salt and half a glass of water. 1) How would they make salt solutions? 2) Who would be able to prepare a saturated solution?
Answer: To make a salt solution, mix the salt in water and by continuous stirring results in a salt solution.... View Article
Match the mixtures in column I with their method of separation in column II.
Column I Column II (a) Oil mixed in water (i) Sieving (b) Iron powder mixed with four (ii) Hand-picking (c)... View Article
Name and describe briefly a method which can be helpful in separating a mixture of husk from grains. What is the principle of this method?
Answer: By using the process of winnowing, the husk can be separated from grains. When the mixture is allowed to... View Article
State whether the following statements are true or false. (a) A mixture of oil and water can be separated by filtration. (b) Water can be separated from salt by evaporation. (c) A mixture of wheat grains and wheat flour can be separated by sieving. (d) A mixture of iron filings and rice flour can be separated by a magnet. (e) A mixture of wheat grains and rice flakes can be separated by winnowing. (f) A mixture of tea leaves and milk can be separated by decantation.
Answer: (a) A mixture of oil and water can be separated by filtration. – False. Since a mixture of oil... View Article
Fill in the blanks with appropriate word. Filtration is helpful in separating an insoluble_______from a______.
Answer: Filtration is helpful in separating an insoluble solid from a liquid. Filtration is the most common method of separating... View Article
Fill in the blanks with appropriate word. The process of settling of heavier particles is called_____.
Answer: The process of settling of heavier particles is called sedimentation. Sedimentation is defined as the separation process in which... View Article
Fill in the blanks with appropriate word. Husk from wheat flour is generally removed by______
Answer: Husk from wheat flour is generally removed by sieving. Sieving allows the fine flour particles to pass through the... View Article
Fill in the blanks with appropriate word. ____ are obtained from stalks by threshing.
Answer: Grains are obtained from stalks by threshing. Threshing is the process that is used to separate the grain from... View Article
Fill in the blanks with appropriate word. Small pieces of stone can be removed from rice by_____.
Answer: Small pieces of stone can be removed from rice by handpicking. We come across many instances in our daily... View Article
Sheela, Saima and Ravi have to dissolve the maximum amount of sugar in the same amount of milk so as to win in a game. Ravi took hot boiling milk while Saima took ice-cold milk. Sheela managed to get milk at room temperature. Whom do you think would win the game and why?
Answer: The solubility of solids in liquids increases with temperature. Ravi would win the game because he will be able... View Article
Paheli asked for a glass of water from Boojho. He gave her a glass of ice-cold water. Paheli observed some water droplets on the outer surface of the glass and asked Boojho how these droplets of water were formed. Which of the following should be Boojho’s answer? (a) Evaporation of water from the glass. (b) Water that seeped out from the glass. (c) Evaporation of atmospheric water vapour. (d) Condensation of atmospheric water vapour.
Answer: (d) Condensation of atmospheric water vapour. The droplets of water were formed when the air reaches the surface of... View Article
During summer, Boojho carries water in a transparent plastic bottle to his school. One day he left his bottle in the school. The bottle still had some water left in it. The following day, he observed some water droplets on the inner surface of the empty portion of the bottle. These droplets of water were formed due to (a) boiling and condensation (b) evaporation and saturation (c) evaporation and condensation (d) condensation and saturation.
Answer: (c) evaporation and condensation The water droplets were formed due to high temperature in summers; the water gets heated... View Article
