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Boojho took an empty plastic bottle, turned it upside down and dipped its open mouth into a bucket filled with water. He then tilted the bottle slightly and made the following observations. (i) Bubbles of air came out from the bottle. (ii) Some water entered the bottle. (iii) Nitrogen gas came out in the form of bubbles and oxygen got dissolved in water. (iv) No bubbles formed, only water entered the bottle. Which observations is/are correct? (a) (i) and (ii) (b) (iv) only (c) (iii) and (iv) (d) (i) only

(i) Bubbles of air came out from the bottle. (ii) Some water entered the bottle. Explanation When the bottle was... View Article

What is not true about the air? (a) It makes the windmill rotate. (b) It helps in the movements of aeroplanes. (c) Birds can fly due to the presence of air. (d) It has no role in the water cycle.

d) It has no role in water cycle Explanation The water cycle, also known as the hydrologic cycle or the hydrological... View Article

Wind does not help in the movement of which of the following? (a) Firki (b) Weathercock (c) Ceiling fan (d) Sailing yacht

Wind help in the movement of firki, weather cock and sailing yacht but it does not play any role in... View Article

Which of the following statements is incorrect? (a) All living things require air to breathe. (b) We can feel air but we cannot see it. (c) Moving air makes it possible to fly a kite. (d) Air is present everywhere but not in soil.

Air is present everywhere, it is omnipresent in nature. We can know this by taking a lump of soil in... View Article

Which one out of beetles, roundworm and earthworm are used for vermicomposting and why?

The animal used for vermicomposting is earthworm. They convert waste from plants and animals or their products into compost or... View Article

Who, out of the following should properly dispose of the garbage – father, mother, elder brother, younger sister?

All the members of the family should dispose garbage properly. It is the duty of every person in the society... View Article

Why should we prefer to use paper bags rather than polythene bags?

We should prefer paper bags rather than polythene bags because paper is biodegradable and can be recycled, but polythene bags... View Article

What happens when? i) cooking medium is made to flow down a drain ii) insecticide, motor oil, paints are poured down the drain iii) tea leaves, cotton swabs and old soft toys are thrown into the drain.

a. If cooking medium is made to flow down a drain it may clog the pores of soil or may... View Article

Why should we not burn plastic items?

Burning of plastic items produce dangerous toxic gases which cause health hazards as well as environmental pollution. The gases released... View Article

Recently, a ban on plastic bags has been imposed in many places? Is the ban justified? Give reasons in three sentences.

Plastic ban is justified as- Plastic is non-biodegradable waste. People throw plastic in rivers and seas which causes threat to... View Article

Beautifully handcrafted articles like boxes and toys are made of paper pulp in our country. Can you explain how paper pulp which is made from paper can be used to make hard boxes and other articles?

Hard boxes and other articles can be made by using paper pulp by followings ways- a. First we can make... View Article

Write 3 sentences on what comes to your mind when you chance to see the following. (a) A rag picker. (b) A cow eating a polythene bag. (c) A foul odour emanating from garbage at the entrance of your house.

a. When I see a rag picker I think he might be poor not able to get enough food so... View Article

Given below are steps in vermicomposting and each step has been given an alphabet. Rearrange the steps in the correct sequence and write the alphabets on the chart provided. One step is done for you. F Dig a pit in a suitable place, in your garden. C Spread sand on the floor of the pit. E Add vegetable peels and fruits waste in the pit. A Sprinkle water to keep it moist D Place red worms in the pit B Cover with a gunny bag or grass Step 1 – F

Correct steps of vermicomposting are – 1 – F Dig a pit in a suitable place in your garden. 2 –... View Article

Beera, a farmer would clear his field every day, and burn dry leaves fallen on the ground. After some time he found that those living in huts near his field were suffering from cough and breathing problems. (i) Can you explain why? (ii) Also, suggest an environment-friendly way to dispose of the dry leaves.

(i) Burning of leaves releases harmful and toxic gases and creates a lot of smoke that causes diseases in humans... View Article

Fill in the blanks to make the statement true: When converted into percentage, the value of 6.5 is _________ than 100%.

Answer: When converted into a percentage, the value of 6.5 is more than 100%. Given: 6.5 = 6.5 × 100... View Article

Fill in the blanks to make the statement true: The _________ of interest on a sum of ₹ 2000 at the rate of 6% per annum for 11/2 years and 2 years is ₹ 420.

Answer: The sum of interest on a sum of ₹ 2000 at the rate of 6% per annum for 1½... View Article

Fill in the blanks to make the statement true: To convert a decimal into a percent, we shift the decimal point two places to the _________.

Answer: To convert a decimal into a percent, we shift the decimal point two places to the right. In mathematics,... View Article

Fill in the blanks to make the statement true: To convert a fraction into a percent, we _________ it by 100.

Answer: To convert a fraction into a percent, we multiply it by 100. Percentage In mathematics, a percentage is a... View Article

Fill in the blanks to make the statement true: The difference of interest for 2 years and 3 years on a sum of ₹ 2100 at 8% per annum is _________.

Answer: The difference of interest for 2 years and 3 years on a sum of ₹ 2100 at 8% per... View Article

Fill in the blanks to make the statement true: Interest = (P × R × T)/100, where T is R % is and P is __________

Answer: Interest = (P × R × T)/100, where T is R % is and P is Principal. Example: Interest... View Article

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