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Why is air called breath of life? Enumerate functions of air or atmosphere.
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Name the scientist who gave law of conservation of mass.
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Name the law of chemical combination which was given by Lavoisier.
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Name the law of chemical combination which was given by Proust.
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Which of the following terms apply to sound waves in air and which to water waves?
Transverse, Rarefaction, Trough, Crest, Compression, Longitudinal
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Name the three subatomic particles present in an atom.
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What is the usual symbol for (a) and electron (b) a proton, and (c) a neutron?
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‘If 100 grams of calcium carbonate (whether in the form of marble or chalk) are decomposed completely, then 56 grams of calcium oxide and 44 grams of carbon dioxide are obtained’. Which law of chemical combination is illustrated by this statement ?
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What are the building blocks of matter ?
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How is the size of an atom indicated ?
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Name the unit in which the radius of an atom is usually expressed.
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Write the relation between nanometre and metre.
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Why is it not possible to see an atom even with the most powerful microscope ?
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When we open a gas tap of a few seconds, the sound of escaping gas is heard first but the smell of gas comes later. Why?
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Explain why, a ringing bell suspended in a vacuum chamber cannot be heard outside.
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The frequency of the sound emitted by the loudspeaker is 1020 Hz. Calculate the wavelength of the sound wave in air in cm where its velocity is 340 m/s.
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Fill in the following blanks with suitable words :
In water, the proportion of oxygen and hydrogen is .............. by mass.
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Describe an experiment to show that sound cannot pass through vacuum.
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How many times is a proton heavier than an electron?
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An electric bell is suspended by thin wires in a glass vessel and set ringing. Describe and explain what happens if the air is gradually pumped out of the glass vessel.
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