CBSE Guess > Papers > Important Questions > Class IX > 2009 > Science > Science By : Mr M. p. Keshri
CBSE CLASS I X
Atoms And Molecules (Solved)
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Q. 65. State the chemical name, chemical formula for the following compounds :
Baking soda, Washing soda, Blue vitriol, Green vitriol, Lime water, Marble chips, Soda ash, White vitriol or Oil of vitriol, Gypsum.
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Q. 66. Define molecular formula. What is significance of a formula ?
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Q. 67. The chemical formula of calcium oxide is CaO and not Ca2O2. Why ?
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Q.68. Write down the formula of :
(i) Aluminium nitride
(ii) Aluminium phosphate
(iii) Calcium carbonate
(iv) Barium sulphate.
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Q. 69. Write down the formula of :
(i) Sodium carbonate
(ii) Aluminium oxide
(iii) Aluminium chloride
(iv) Hydrogen sulphide
(v) Calcium hydroxide
(vi) Ammonium sulphate
(vii) Calcium bicarbonate
(viii) Ammonium phosphate
(ix) Silver nitrate.
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Q. 70. Write down the name of the compounds given by the following formulae :
(i) CaCO3
(ii) (NH4)2CO3
(iii) H2CO3
(iv) SO2 (v) Al2(SO4)3
(vi) MgCl2
(vii) K2SO4
(viii) KNO3
(ix) CaCl2
(x) PbNO3.
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Q. 71. Write down the formula of :
(i) Sodium oxide
(ii) Aluminium chloride
(iii) Sodium sulphide
(iv) Magnesium hydroxide.
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Q. 72. Write down the names of the compounds represented by the following formulae :
(i) Al2(SO4)3
(ii) CaCl2
(iii) K2SO4
(iv) KNO3
(v) CaCO3.
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Q. 73. What is meant by the term chemical formula ?
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Q. 74. How many atoms are present in a
(i) H2S molecule and
(ii) PO43- ion ?
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Q. 75. What is ‘Molecular Mass’ ?
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Q. 76. What is formula unit mass ?
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Q. 77. Atomic masses of some elements are given as under :
Hydrogen (H) = 1u; Carbon (C) = 12u; Oxygen (O) = 16u; Nitrogen (N) = 14u;
Sodium (Na) = 23u; Magnesium (Mg) = 24u; Fluorine (F) = 19u;
Chlorine (Cl) = 35.5u; Calcium (Ca) = 40u.
Find the molecular mass of the following :
CH4, C2H2, CH3OH, CO2, H2O, Na2O, MgCl2, NaF, CaCO3, Mg(NO3)2,
NaNO3, Na2CO3, H2, O2, Cl2.
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Q. 78. Explain the term ‘mloe concept’.
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Q. 79. What is the use of mole concept ?
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Q. 80. State Avogadro number.
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Q. 81. What is gram atom ? How is it related to the mole and Avogadro number ?
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Q. 82. State the term ‘gram molecular mass’. How is it related to the mole and Avogadro number ?
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Q. 83.How will you explain that gram atomic mass or gram molecular mass of any substance contains the same number of particles ?
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Q. 84. Atomic mass of C-12 is 12u. On the basis of mole concept, express 1u into grams.
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Q. 85. Is the weight of 1 mole of sodium and 1 mole of oxygen the same ?
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Q. 86. What is number of grams in 0.2 moles of water ?
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Q. 87. Calculate the mass of the following in grams :
(i) 0.5 mole of sulphuric acid
(ii) 0.5 mole of aluminium sulphate
(iii) 0.5 mole of ammonia
(iv) 2 moles of hydrogen chloride.
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Q. 88. Calculate the ratio of moles of 3.6 g of water and 4.4 g of carbon dioxide.[Atomic mass of C = 12u, H = 1u, O = 16u].
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Q. 89. How many mole atoms of oxygen are present in one mole each of potassium chlorate, sodium sulphate, nitric acid and aluminium sulphate ?
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Paper By Mr. M. P. Keshari [ For Further Enquiry 09434150289]
