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A four-digit number aabb is divisible by 55. Then possible value(s) of b is/are (a) 0 and 2 (b) 2 and 5 (c) 0 and 5 (d) 7

Answer: (c) 0 and 5 It is known that if a four-digit number aabb is divisible by 55, then the number should be divisible by the factors of 55.... View Article

The sum of all the numbers formed by the digits x, y and z of the number xyz is divisible by (a) 11 (b) 33 (c) 37 (d) 74

Answer: (c) 37 It is known that, three numbers which can be formed by the using the digits x, y and z are xyz, yzx and zxy. The general form of... View Article

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 The general representation of a number is as follows: For a two-digit number say AB A × 10 + B × 1 For a three-digit... View Article

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 x b + 1 x c, which is equal 1000a + 10b + c The general... 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 respective place value. So the generalised form of... 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 the sum of the product of it digits with the respective place... 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 be handpicked or removed by a... 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 from the mixture which is floating. Hence... 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 healthy wheat crop ready for... 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 following... 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. Mohan will be able to prepare a... 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) Salt mixed with water (iii)... 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 fall down from a height, the... 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 and water can be separated by a separating... 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 to dissolve the maximum... View Article

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