Definitions and mcqs of ninth class chemistry (chemical combinations)

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Comprehensive chemistry notes for Ninth Class Chemistry

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Definitions and mcqs of ninth class chemistry (chemical combinations)

  1. 1. Chapter 2Chemical Combinations(You can neither stop nor save the time butcan make every moment historical if youknow the value of time)Chemistry MCQs Dr. Sajid Ali Talpur
  2. 2.  Definitions1. Atomic mass: - Atomic mass is defined as themass of one atom of the element compared withthe mass of one atom of C12 (the stable lightisotope of carbon).2. Molecular mass: - It is defined as the sum ofatomic masses of the atoms of all the elementspresent in a molecule shown by its molecularformula.3. Empirical formula mass/ formula mass: - It isthe sum of atomic masses as given in thesimplest (empirical) formula of ionic compound4. Molecular formula: - The expression, showingtypes and actual number of atoms present in acompound, using symbols for componentelements and numerals for number of atoms ofeach element per molecule, like C6H6 forbenzene.5. Empirical formula: - A chemical formula thatindicates the relative proportions of the elementsin a compound rather than the actual number ofthe atoms of the elements.6. Mole: - One mole is gram atomic mass, grammolecular mass or gram formula mass of anysubstance (atoms, ions, molecules), whichcontains 6.02*1023elementary entities.Chemistry MCQs Dr. Sajid Ali Talpur
  3. 3. 7. Molar mass: - The mass of one mole is calledmolar mass.8. Avagadro’s number: - The number of basicquantities as present in 12 grams of C12i.e6.02*1023 Multiple Choice Questions1. Mass can not be created but can be destroyed.a) true b) false2. Landolt experiment is performed to verify:a) law of conservation of massb) law of definite proportionsc) law of multiple proportionsd) law of reciprocal proportions3. The empirical formula of glucose is:a) CH b) CH2Oc) C3H6O6 d) C6H12O64. The empirical formula mass of benzene is:a) 12 a.m.u b) 13 a.m.uc) 78 a.m.u d) N.O.T5. Molecular mass of sodium is:a) 11 a.m.u b) 12 a.m.uc) 23 a.m.u d) N.O.TChemistry MCQs Dr. Sajid Ali Talpur
  4. 4. 6. ______moles are there In 50 g of CaCO3.a) 0.5 b) 1c) 1.5 d) 1.57. 3 moles of Carbon are equal to:a) 4g b) 36gc) 132g d) 18.06*10238. Zn + HCl → ZnCl2 + H2. The reaction is anexample of:a) decomposition reactionb) addition reactionc) single displacement reactiond) double displacement reactione) combustion reaction9. Chemical equation is a short hand method fordescribing a compound.a) true b) false10. Combustion reaction consumes heat:a) true b) falseThe book MCQs11. mass is neither created nor destroyed during achemical reaction is the statement of:a) law of conservation of massb) law of definite proportionsc) law of multiple proportionsd) law of reciprocal proportionsChemistry MCQs Dr. Sajid Ali Talpur
  5. 5. 12. a given compound always contains exactly thesame proportion of elements by mass is thestatement of:a) law of conservation of massb) law of definite proportionsc) law of multiple proportionsd) law of reciprocal proportions13. the average mass of natural mixture of isotopes,which is compared to the mass of one atom ofC-12 a.m.u is called:a) atomic number b) atomic massc) mass number d) molecular mass14. a formula that gives only the relative number ofeach type of atoms in a molecule is called:a) empirical formula b) molecular formulac) molecular mass d) formula mass15. a formula that indicates actual number and typeof atoms in a molecule is called:a) empirical formula b) molecular formulac) molecular mass d) formula mass16. the sum of atomic masses of all atoms in amolecule is called:a) empirical formula b) molecular formulac) molecular mass d) formula mass17. the sum of atomic masses of all atoms in aformula unit:a) empirical formula b) molecular formulac) molecular mass d) formula massChemistry MCQs Dr. Sajid Ali Talpur
  6. 6. 18. the mass of one mole of a substance expressedin grams is called:a) empirical formula b) molecular formulac) molecular mass d) molar mass19. 44 a.m.u of CO2 is equal to:a) formula mass b) atomic massc) molecular mass d) molar mass20. 5 moles of H2O are equal to:a) 80g b) 90gc) 100g d) 90a.m.uAnswer Key1 B 2 A 3 B4 B 5 D 6 A7 B 8 C 9 B10 B 11 A 12 B13 B 14 A 15 B16 C 17 D 18 D19 C 20 DChemistry MCQs Dr. Sajid Ali Talpur
  7. 7. 18. the mass of one mole of a substance expressedin grams is called:a) empirical formula b) molecular formulac) molecular mass d) molar mass19. 44 a.m.u of CO2 is equal to:a) formula mass b) atomic massc) molecular mass d) molar mass20. 5 moles of H2O are equal to:a) 80g b) 90gc) 100g d) 90a.m.uAnswer Key1 B 2 A 3 B4 B 5 D 6 A7 B 8 C 9 B10 B 11 A 12 B13 B 14 A 15 B16 C 17 D 18 D19 C 20 DChemistry MCQs Dr. Sajid Ali Talpur

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