Description : In severe winter, in cold countries water pipes burst because – (1) Water expands on freezing (2) Contraction of water pipes (3) High atmospheric pressure (4) Combined effect of all the above three
Last Answer : (1) Water expands on freezing Explanation: Most liquids have a quite simple behavior when they are cooled (at a fixed pressure): they shrink. The liquid contract as it is cooled; ... substance solidifies, which causes it to contract some more because crystalline solids are usually tightly packed.
Description : In severe winter, in cold countries water pipes burst because (1) water expands on freezing (2) contraction of water pipes (3) high atmospheric pressure (4) combined effect of all the above three
Last Answer : water expands on freezing
Description : Why does an egg (with the shell) burst when cooked in a microwave oven?
Last Answer : Microwave radiation is generated in an electronic tube called a magnetron, and passes along what's called a wave-guide into the oven cavity. The microwaves are absorbed by foods - a characteristic that ... encourages even cooking and (if we forget to prick the yolk) helps to confine the explosion.
Description : Why does steam cause more severe burns than boiling water?
Last Answer : Ans: The amount of heat (latent heat) possessed by steam is much greater than the amount of heat possessed by water at the same temperature. Therefore, steam causes more severe burns than boiling water
Description : Why water pipes burst in a cold country ?
Last Answer : Water pipes rupture in cold countries because: When water freezes and freezes in cold countries, there are many difficulties to increase its volume. As the ice melts, the volume increases, so more pressure is felt on the water pipe and it breaks. This is because there is no air inside the pipe.
Description : Water pipes in hilly areas often burst on a cold frosty night, because – (1) The material of which pipes are made contracts due to cold and so breaks (2) Water in the pipes freezes and on freezing water expands, so pipes break (3) Frost makes the pipes rusty, so they break (4) None of these
Last Answer : (2) Water in the pipes freezes and on freezing water expands, so pipes break Explanation: The temperature may fall below 0° C during cold frosty nights which converts the water inside the pipes into ice, ... in an increase in volume. This exerts great force on the pipes and as a result, they burst.
Description : Water pipes in hilly areas often burst on a cold frosty night, because (1) the material of which pipes are made contracts due to cold and so breaks (2) water in the pipes freezes and on freezing water expands, so pipes break (3) frost makes the pipes rusty, so they break (4) None of these
Last Answer : water in the pipes freezes and on freezing water expands, so pipes break
Description : Why does a liquid remain hot or cold for a long time inside a thermo flask?
Last Answer : Ans: Because of the presence of air, which is poor conductor of heat, in between the double glass walls of a thermos flask.
Description : A cold compress is applied on the forehead of a person suffering from high fever. Why?
Last Answer : Ans: Evaporation causes cooling. As the water evaporates, it absorbs heat from the forehead and helps in reducing the temperature.
Description : Why are the areas lying between the Arctic Circle and the North Pole in the Northern Hemisphere and the Antarctic Circle and the South Pole in the Southern Hemisphere very cold?
Last Answer : Ans: These areas are very cold because the sun does not rise much above the horizon. Therefore, its rays are always very slanting which emit minimum heat. These areas being very cold are called Frigid Zones.
Description : Why are winters more severe in Southern Hemisphere than in Northern Hemisphere? (1) Earth is titled towards the sun in the Northern Hemisphere (2) Northern Hemisphere receives more sunlight (3) Because of more iceberg activity in Southern Hemisphere (4) Southern Hemisphere is less inhabited
Last Answer : (1) Earth is titled towards the sun in the Northern Hemisphere Explanation: The winter in the Southern Hemisphere occurs when the Northern hemisphere is tilted more toward the Sun. From the perspective of an ... the Earth, the winter Sun has a lower maximum altitude in the sky than the summer Sun.
Last Answer : Earth is titled towards the sun in the Northern Hemisphere
Description : How long does it take for pipes to freeze and burst?
Last Answer : I would say it takes hours with no heating when the temperature is below -15...I believe 48 hours would be enough, especially if your house is not well insulated. It is always important to ... also essential to avoid this kind of thing. Experience from living in -35 temperatures + plumber friend
Description : Why does sea water not erode coastal areas in all places?
Last Answer : The main cause of coastal erosion is the kinetic energy of wind. The main medium of transmission of wind energy is through wind generated water waves. Occasionally waves are also generated by other ... littoral drift (as in Chennai Marina), stopped by the harbour structures jutting into the sea.
Description : What is meant by ozonised mineral water?
Last Answer : Ozone is a blue gas with a relative molar mass of 48 and molecular formula of O {-3}. It converts back into oxygen after its oxidising process. This makes it the most eco-friendly treatment ... control rate of injection. The amount of ozone to diffuse in water depends on the contamination of water.
Description : Since clouds contain tiny water droplets, why are rainbows not permanently present?
Last Answer : On a rainy day, sunrays, which are polychromatic(with all the seven colours), fall on water droplets at a certain incident angle adn refract with certain other refractive angle because water ... they are numerous and closer against an appropriate viewing angle to allow the cooperative phenomenon.)
Description : Why are fishes not able to survive in distilled water?
Last Answer : Take a fresh grape fruit and keep it in distilled water for an hour. It is stouter than before. Another fresh grape fruit kept in salty water for an hour will appear slim and wrinkled. The grape has ... of being blown out if the fish is to be in distilled water for a very long period of time.
Description : Oil and water do not mix. Why?
Last Answer : Ans: i) Molecules of oil are not bigger than that of water and therefore do not mix easily. ii) Molecules of water are polar, i.e. they have opposite charges at two ends whereas oil molecules do not; as a consequence they tend to stay away from water molecule.
Description : Why is it recommended to add salt in water while boiling grams?
Last Answer : Ans: By addition of salt the boiling point of water gets which helps in cooking.
Description : Why is the boiling point of sea water more than that of pure water?
Last Answer : Ans: Sea water contains salts and other impurities with different points which jointly rise its boiling point.
Description : A piece of chalk when immersed in water, emits bubbles. Why?
Last Answer : Ans: Chalk consists of pores forming capillaries. When it is immersed in water, the water begins to rise in the capillaries and air present there is expelled in the form of bubbles.
Description : Why is it easier to spray water to which soap is added?
Last Answer : Ans: Addition of soap decreases the surface tension of water. The energy for spray is directly proportional to surface tension.
Description : It is easier to swim in sea water than in river water. Explain.
Last Answer : Ans: The density of sea water is more than that of the river water. Therefore, the weight of sea water displaced by the swimmer is more. Thus, buoyant force of upthrust on the swimmer increases, making it easier to swim in sea water.
Description : It is difficult for firemen to hold a hose, which ejects large amount of water at a high velocity. Why?
Last Answer : Ans: the water which comes out of the fireman's hose carries large momentum as its velocity is very high. The equal and opposite reaction force pushes the fireman backwards with a great speed satisfying ... of conservation of momentum. As a result, it is difficult for the fireman to hold the hose.
Description : Why does an iron needle float on clean water but sink when some detergent is added to this water?
Last Answer : Ans: Due to surface tension, the free surface of liquid at rest behaves like a stretched membrane. When an iron needle floats on the surface of clean water, its weight is supported by the stretched ... weakened and is not able to support the weight of needle. Hence the needle sinks in such water.
Description : Rain water is more fertile than water from tube well.
Last Answer : Ans: Rain water is more fertile because it contains many salts and nitrogen dissolved from the atmosphere.
Description : Water boils quicker on mountains.
Last Answer : Ans: On Mountains the pressure of the air is low due to height, as the air pressure decreases with altitude. In this way, water boils quicker on mountains at temperature less than 100 degree centigrade, which is the boiling point of water at ground level.
Description : Water remains cool in earthen pitcher.
Last Answer : Ans: This occurs due to the process of evaporation. Water gets cooled on evaporation. As the earthenware pitcher is concerned, they have small pores. Water tends to come out of pores and evaporates which ... Besides metal has tendency to absorb heat that why water does not get cooled in a metal pot.
Description : What causes milk to rise up when we boil it?
Last Answer : Milk contains 87 per cent water, 4 per cent proteins and 5 per cent lactose (milk sugar). When we boil milk, the fat, sugar, proteins and minerals get separated. Since they are lighter than ... vapour pressure raises the creamy layer. So the milk pushes the creamy layer out and milk spills out.
Description : How does a compact fluorescent lamp consume less electricity than conventional fluorescent lamps and bulbs?
Last Answer : Fluorescent lamps are based on the phenomenon of gas discharge between two electrodes at the ends of a glass tube. Generally these tubes contain a little mercury in the low-pressure vapour phase. When ... poor efficiency. The three types of lamps may have a typical efficiency ratio of 8:6:3.
Description : Why is fuel used in airplanes different from those used in motor vehicles?
Last Answer : Aviation turbine fuels are used for powering jet and turbo-prop engine aircraft. Kerosene was used to fuel the first turbine engines. Kerosene-type fuel was chosen as having the best ... is only significant demand in very cold climates where its better cold weather performance is important.
Description : How does a rechargeable battery work? What is the life of such batteries and how are they different from ordinary batteries?
Last Answer : Electrochemical cells and batteries are identified generally as primary and secondary batteries. The primary batteries cannot be easily or effectively re-charged electrically and hence are discharged (used ... cycles (one cycle represents one discharge and charge) depending on its design parameters.
Description : What is the peculiar smell of the earth after the first shower?
Last Answer : ANSWER I: The characteristic earthy odour of soil is caused by the production of a series of streptomycete metabolites called geosmins. These substances are sesquiterpenoid compounds and unsaturated compound ... ) is the microbial product found in the spores is responsible for the pleasant smell.
Description : How is a ventriloquist able to throw his voice?
Last Answer : ANSWER I : Ventriloquism is the art of projecting or `throwing,' the voice so that is appears to come from a different source. The performer also directs the attention of the audience to the place from where ... of light that hits it, while the ear isn't so sensitive to the direction of a noise.
Description : Does frequent switching on/off of a fluorescent lamp reduce its life?
Last Answer : The life of a fluorescent lamp is essentially determined by life of the cathode filament it uses. A conventional fluorescent lamp employs closely wound coil of tungsten wire as filament. Upon switching on ... of continuous burning can be halved or made still less, just by frequent switching on/off.
Description : How do touch screens work?
Last Answer : Touch screen monitors - where you can use your finger on the computer screen to navigate through the contents - have become more and more commonplace over the past decade, particularly at public information ... allowing a touch with almost any object - except hard and small objects like a pen tip.
Description : How does the solar wind affect Earth?
Last Answer : Solar wind contains intense clouds of high energy particles which are produced by solar storms. These clouds of particles affect Earth. These clouds are called coronal mass ejections. They reach the earth ... by the solar wind, especially the storm clouds that the Sun launches our way very often.
Description : Why is the @ symbol used in an email address?
Last Answer : ANSWER I: The e-mail address generally has two parts, user id and the domain name. The @ (at) symbol is used to separate the user id from the domain name in the e-mail address. The e- ... reached on the Internet by giving the email address (also called the User's Uniform Resource Locator (URL)).
Description : What is Polaroid sunglasses made of?
Last Answer : ANSWER I: Polaroids are thin and large sheets of crystalline polarising material (made artificially) capable of producing plane polarised beams of large cross section. As early as 1852, it was ... to return to their original shape, resulting in the loss of their light absorbing properties.
Description : Why does rain come in drops and not in a continuous stream?
Last Answer : When warm wet air rises, it cools and water vapour condenses to form clouds. A cloud is made of small drops of water or ice crystals, depending on its height and how cold its surrounding air is. ... Giant droplets fall rapidly. Thus drops keep on falling side by side and not in a continuous stream.
Description : Why is the Earth's core hot? What caused it to heat up? Is it still heating, or now cooling?
Last Answer : Scientists estimate that temperature at the Earth's core is about 5538{+0}C. Much of the heat inside the Earth today comes from elements that were present when the planet was first formed billions of years ... function of their half-life. Therefore, Earth's core is not heating up, it's cooling down.
Description : How is carbon dioxide removed from blood before it is exhaled?
Last Answer : In humans, carbon dioxide is generated in the tissues during oxidation of glucose, in order to liberate energy, which is resumed to perform body functions. Before exhalation through lungs the gas is transported ... than the tissue capillaries. Nearly 23 per cent of CO{-2} is transported this way.
Description : How do certain species of birds such as Humming Birds, Terns, Gulls and Kestrels remain in the air without a forward motion?
Last Answer : ANSWER I: The humming bird's wings consist mainly of elongated hand bones to which the flight feathers are attached, and the whole wing can rotate as does the wrist. The short arm bones not ... only birds which can fly forwards, backwards, up, down, sideways or move instantaneously in any direction.
Description : How does ballast-less track provide safe travel?
Last Answer : ANSWER I: Ballast is a prime component of the track that acts as a vibrant medium to transmit from the rail surface the weight of the train down to the formation, the wells set on ... cost involved in laying a ballast-less track is more initially but it requires less recurring maintenance cost.
Description : What is Computer Simulation Technique?
Last Answer : ANSWER I: `Simulation' in general terms can be defined as the representation or imitation of a system in its realistic form. When a computer program is used to create a model to mimic a ... frame, combustion, and weather and ocean circulation are some of the examples that need huge computer power.
Description : Do animals also have blood groups like humans?
Last Answer : In man blood group is applied to single factor. This factor is agglutinogen and is also called antigen. It is found on the surface of red blood corpuscles. Accordingly a person with `A ... set off strong transfusion reactions. Such reaction can occur on the second or on subsequent blood transfusion.
Description : How does scratching cure itching sensation?
Last Answer : Very sensitive, rapidly adapting, mechanoreceptive free nerve endings that elicit only the tickle and itch sensation are found almost exclusively in the superficial layers of the skin. This sensation ... The anterolateral system is a cruder type of transmission system than the dorsal column system.
Description : In the past, why was injection administered in the stomach for dog bite?
Last Answer : ANSWER I: This is the only disease where the vaccine is given after the exposure (post- exposure). Nervous tissue vaccine (NTV), is one of the vaccines administered for dog bite. This vaccine is ... it does not require a subcutaneous layer. Hence, it can be given in the buttocks or arm region.
Description : What is the pH of rainwater? Is the pH suitable for drinking?
Last Answer : The technical definition of pH is that it is a measure of the activity of the hydrogen ion (H+). It is essentially a measure of acidity. The pH scale ranges from 0 -14. In the ... of rainwater tends to fall drastically, rainfall is highly acidic and the water thereby becomes unfit for consumption.
Description : What is the difference between TV screen and computer monitor?
Last Answer : ANSWER I: Computer monitors are capable of accepting signals only from the central processing unit of a computer. Therefore they are unable to reproduce a colour image from a composite video signal ... prevent flicker. This requires electronics that operate twice the speed as that of a television.