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question_answer1) When do zeros present in a number become insignificant?
question_answer2) Is velocity a basic or derived quantity according to S.I. system?
question_answer3) Which is more precise measurement of the length of a thread (i) 10.0 cm (ii) 10.00 cm?
question_answer4) Why do we regard the gaseous state of water as vapours while that of ammonia as gas?
question_answer5) Why is distilled water a compound while tap water a mixture?
question_answer6) Mixture of salt and water is a solution while that of oil and water is not. Explain.
question_answer7) When is the law of definite proportions not obeyed?
question_answer8) Which law co-relates the mass and volume of a gas?
question_answer9) Atomic mass of oxygen is 16 u. What does its indicate?
question_answer10) An element has fractional atomic mass. What does it indicate?
question_answer11) What is the difference between the mass of a molecule and molecular mass?
question_answer12) Where do we use the words mole and mol?
question_answer13) Does one gram mole of a gas occupy 22.4 L under all conditions of temperature and pressure?
question_answer14) What is the basic difference between empirical and molecular formulae?
question_answer15) The percentages of all the elements present in a compound are 92. What does it indicate?
question_answer16) Why is it necessary to balance a chemical equation?
question_answer17) In the combustion of methane, why is methane regarded as the limiting reactant?
question_answer18) What is the difference between molarity and molality?
question_answer19) Classify the following substances into elements, compounds and mixtures : (i) Milk (ii) 22-carat gold (iii) Iodized table salt (iv) Diamond (v) Smoke (vi) Steel (vii) Brass (viii) Dry ice (ix) Mercury (x) Air (xi) Aerated drinks (xii) Glucose (xiii) Petrol/Diesel/Kerosene oil (xiv) Steam (xv) Cloud.
question_answer20) Why is air sometimes considered as a heterogeneous mixture?
question_answer21) What physical quantities are represented by the following units and what are their most common names? (i) \[kg\,m\,{{s}^{-2}}\] (ii) \[kg\,{{m}^{2}}\,{{s}^{-2}}\] (iii) \[d{{m}^{3}}\]
question_answer22) Rewrite the following after necessary corrections: (i) The length of a rod is 10 cms. (ii) The work done by a system is 10 Joules.
question_answer23) Given that density of water is \[1\,g\,m{{L}^{-1}}\]. What is its density in \[kg\,{{m}^{-3}}\]?
question_answer24) What is the difference between the following? (i) \[2\cdot 5\,\times {{10}^{3}}\,g\]and\[2\cdot 50\,\times {{10}^{3}}g\] (ii) 160 cm and 160.0 cm.
question_answer25) Why Law of conservation of mass should better be called as Law of conservation of mass and energy?
question_answer26) Is the law of constant composition true for all types of compounds? Explain why or why not.
question_answer27) 1 L of a gas at S.T.P. weighs 1.97 g. What is the vapour density of the gas?
question_answer28) What is the difference in the molar volume of a gas if S.T.P. conditions are (i) \[1\,\,atm,\,\,0{}^\circ C\] (ii)\[1\,\,bar,\,\,0{}^\circ C\]?
question_answer29) Why atomic masses are the average values?
question_answer30) Why are the atomic masses of most of the elements fractional?
question_answer31) What is die difference between the mass of a molecule and gram molecular mass?
question_answer32) Two bulbs \[{{B}_{1}}\] and \[{{B}_{2}}\] of equal capacity contain 10g oxygen \[({{O}_{2}})\] and ozone \[({{O}_{3}})\] respectively. Which bulb will have greater number of O-atoms and which will have greater number of molecules?
question_answer33) Which of the following has largest number of oxygen atoms? 1.0 g of O atoms, 1.0 g of \[{{O}_{2}},\,1.0\,g\] of ozone\[({{O}_{3}})\]. Justify your answer.
question_answer34) Why molality is preferred over molarity in expressing the concentration of a solution?
question_answer35) Write the formulae and names of three compounds containing same percentage composition of C, H and O.
question_answer36) Determine the equivalent weight of each of the following compounds assuming the formula weights of these compounds are x, y and z respectively. (i)\[N{{a}_{2}}S{{O}_{4}}\] (ii)\[N{{a}_{3}}P{{O}_{4}}.12\,{{H}_{2}}O\] (iii)\[C{{a}_{3}}{{(P{{O}_{4}})}_{2}}\]
question_answer37) An LPG cylinder weighs 14.8 kg when empty. When full, it weighs 29.0 kg and shows a pressure of 2.5 atm. In the course of use at \[27{}^\circ C\], the weight of the full cylinder is reduced to 23.2 kg. Find out the volume of n-butane in cubic meters used up at \[27{}^\circ C\] and 1 atm. (Molecular weight of n-butane = 58).
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