Q&A Bank

Questions & Answers

388 answers across all subjects

Subject:Mathematics Science English Social Studies Hindi Physics Chemistry Biology Computer Science

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ScienceClass 7CBSE

Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce windstorm

Soln: (i) Put heavy stones on it. (ii) Screw it tight.

ScienceClass 7CBSE

When strong/high-speed wind blows, an umbrella held upright at times gets upturned. Explain the reason.

Soln: Umbrella upturns because of the high-speed water passing through umbrella creates low pressure.

ScienceClass 7CBSE

Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.

Soln: The air inside the bottle contracts due to low temperature hence the bottle collapses due to the outside pressure.

ScienceClass 7CBSE

16. Match Column I with Column II. There can be more than one match. Column-I Column-II a) On heating air i) Descends b) On cooling air ii) Expands   iii) Contracts   iv) Rises

Soln: Column-I Column-II a) On heating air ii) Expands b) On cooling air iv) Rises

ScienceClass 7CBSE

A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of the day does this happen – at midnight or in the afternoon?

Soln: Midnight, because of a land breeze.

ScienceClass 7CBSE

A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothesline in the balcony. Towards which direction will the clothes be blown in the afternoon? Explain.

Soln: Because the sea breeze blowing towards the land clothes will be blown towards the house.

ScienceClass 7CBSE

Why is it advisable not to shut all the doors and windows during a storm?

Soln: In order to avoid the roof from getting blown away due to the low pressure created by heavy wind.

ScienceClass 7CBSE

To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why?

Soln: Exhaust fan of B will expel the hot air effectively as air rises up and her fan is at a greater height than A’s.

ScienceClass 7CBSE

State whether the following statements are True or False: (i) If wind flows from land to the ocean, then it is daytime. (ii) A very high-pressure system, with very high-speed wind surrounding it forms a cyclone. (iii) The coastline of India is not vulnerable to cyclones. (iv) Warm air is lighter than cool air.

Soln: (i) False- if the wind blows from land to the ocean, then it is night time because, at night, the water cools down more slowly than the land. So, the cool wind from the land moves towards the ocean. (ii) False – a very low-pressure system, with very high-speed winds revolving around it, forms a cyclone. (iii) False- the whole coastline of India is vulnerable to cyclones, particularly the east coast. (iv) True

ScienceClass 7CBSE

Fill in the blanks. (i) Air around us exerts ______ . (ii) The moving air is called _ . (iii) The main cause of wind movement is uneven _ on the earth. (iv) High-speed wind can cause cyclone in regions of _____ pressure.

Soln: (i) The air around us exerts Pressure. (ii) The moving air is called Wind. (iii) The main cause of wind movement is uneven heating on the earth. (iv) High-speed wind can cause cyclone in regions of low pressure.

ScienceClass 7CBSE

Why is Chandigarh unlikely to be affected by a cyclone?

Soln: Chandigarh is very far from the sea hence it is unlikely to be affected by a cyclone.

ScienceClass 7CBSE

Name the ocean which is mainly responsible for bringing rain-bearing monsoon winds to the Kerala coast in June every year?

Soln: Indian Ocean

ScienceClass 7CBSE

A curtain is hanging at the entrance of a room. A long corridor runs at right angles to the door, which is parallel to the curtain. If a strong wind blows along the corridor, the curtain will (a) get pushed inside the room. (b) get pushed outside the room. (c) get collected towards one end/swirled. (d) remain unaffected.

Soln: The answer is (b) get pushed outside the room. Explanation: If a strong wind blows along the corridor, then the air pressure increases and the curtain gets pushed outside the room.

ScienceClass 7CBSE

Which of the following place is most likely to be affected by a cyclone? (a) Mumbai (b) Puri (c) Goa (d) Porbandar

Soln: The answer is (b) Puri Explanation: Because Puri lies near the coastal area.

ScienceClass 7CBSE

Following are precautions one must take in case a storm is accompanied by lightning. (i) Do not take shelter under a tree. (ii) Do not take shelter under an umbrella with a metallic end. (iii) Do not take shelter in open garages, storage sheds, etc. (iv) Do not take shelter in a bus in the open. Which one of these is not correct? (a) (i) (b) (ii) (c) (iii) (d) (iv)

Soln: The answer is (d) (iv)

ScienceClass 7CBSE

A fire alarm usually detects smoke in case of fire. Where should such an alarm be placed in a room? (a) Near the door (b) On the floor (c) On any wall (d) On the ceiling

Soln: The answer is (d) On the ceiling Explanation: In case of fire, the air above the fire gets heated hence fire alarms are set on the ceiling

ScienceClass 7CBSE

While constructing a house in a coastal area, in which direction should the windows preferably face and why?

Soln: The windows of houses in coastal areas should preferably face towards the sea as sea breeze will keep it cool during day time.

ScienceClass 7CBSE

At a campsite, there are tents of two shades – one made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give a reason for your choice. Would you like to prefer the same tent during winter?

Soln: In summer I would choose a tent with white colour fabric as white is a bad absorber and a good reflector of Heat. But in winter I would choose a tent with black colour fabric as black is a good absorber and bad reflector of heat.

ScienceClass 7CBSE

Why is it advised not to hold the thermometer by its bulb while reading it?

Soln: If we hold the thermometer by its bulb while reading it, the mercury will get expanded by our body temperature.

ScienceClass 7CBSE

You may have noticed that a few sharp jerks are given to clinical thermometer before using it. Why is it done so?

Soln: The jerk will allow the mercury flow into the bulb above kink, which will make mercury level below normal temperature.

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Questions & Answers

Suggest some precautions to be taken to prevent the roof of a tin sheet from flying away during a fierce windstorm

When strong/high-speed wind blows, an umbrella held upright at times gets upturned. Explain the reason.

Paheli kept an empty bottle made of plastic inside a refrigerator. After few hours, when she opened the refrigerator she found the bottle had collapsed. Explain the possible reason.

16. Match Column I with Column II. There can be more than one match. Column-I Column-II a) On heating air i) Descends b) On cooling air ii) Expands &nbsp; iii) Contracts &nbsp; iv) Rises

A flag mounted on a flag post near the sea coast flutters in the direction of sea. At what time of the day does this happen – at midnight or in the afternoon?

A flat in Mumbai with a balcony facing the sea has some clothes hung on a clothesline in the balcony. Towards which direction will the clothes be blown in the afternoon? Explain.

Why is it advisable not to shut all the doors and windows during a storm?

To expel hot air out of the kitchen, ‘A’ has an exhaust fan fitted on the window of her kitchen and ‘B’ has a similar exhaust fan fitted on the wall near the ceiling of her kitchen. Which of the exhaust fan will expel the hot air more effectively? Explain why?

Fill in the blanks. (i) Air around us exerts __________ . (ii) The moving air is called _________ . (iii) The main cause of wind movement is uneven ___________ on the earth. (iv) High-speed wind can cause cyclone in regions of ___________ pressure.

Why is Chandigarh unlikely to be affected by a cyclone?

Name the ocean which is mainly responsible for bringing rain-bearing monsoon winds to the Kerala coast in June every year?

Which of the following place is most likely to be affected by a cyclone? (a) Mumbai (b) Puri (c) Goa (d) Porbandar

A fire alarm usually detects smoke in case of fire. Where should such an alarm be placed in a room? (a) Near the door (b) On the floor (c) On any wall (d) On the ceiling

While constructing a house in a coastal area, in which direction should the windows preferably face and why?

At a campsite, there are tents of two shades – one made with black fabric and the other with white fabric. Which one will you prefer for resting on a hot summer afternoon? Give a reason for your choice. Would you like to prefer the same tent during winter?

Why is it advised not to hold the thermometer by its bulb while reading it?

You may have noticed that a few sharp jerks are given to clinical thermometer before using it. Why is it done so?

16. Match Column I with Column II. There can be more than one match. Column-I Column-II a) On heating air i) Descends b) On cooling air ii) Expands iii) Contracts iv) Rises

Fill in the blanks. (i) Air around us exerts ______ . (ii) The moving air is called _ . (iii) The main cause of wind movement is uneven _ on the earth. (iv) High-speed wind can cause cyclone in regions of _____ pressure.