Ten year of Chapter #01

Quality Education At Every level

 Chapter #01 

Introduction of Chemistry 

 Prepared by:

Lecturer. S.Fayyaz Hussain

             

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 Ph # 021-5449369, 0312-5449369       

2007

1-(a)      Define the following:

                (i) Atomic  Mass.              (ii) Molecular Formula.  (iii) Limiting Reactant.     (iv) Radioactivity.

    (b)      Diethyl zinc is a chemical used in the library to produce the books from the worms. Its                                        composition is 53% zinc, 38.9% carbon and 8.1% hydrogen; find the empirical formula of the                                    compound.

    (c)       find the mass of KCIO₃, required to prepare 3.2 gm of O₂.

2 KCIO_3(s)                              2KCL_(s) + 3O_2(g)

    (d)      (i)            Multiply 4.46 x 1.2 according to multiplication rules,

                (ii)           How many significant figures are there in 0.0821?

                (iii)          What is the mass of 3.01 x 10²² molecules of N₂?

2006

1-(a)      Define the following:

(i)                  Exponential Notation and Significant Number

(ii)                Molecular Formula and Empirical Formula.

(iii)               Stoichiometry and Molar Volume.

    (b)      Give the significant values of the following;

                (i) 685    (ii) 9000                (iii) 0.58                (iv) 0.004

    (c)       An organic compound contains 67.7% of C and 7.41% of H, and 25.90% of N. the molecular mass                                of the compound is 108. Determine the emperical and molecular formulae of the compound.

    (d)      100 grams of KNO₃ are heated to redness. What volume of oxygen at 39⁰C and 765 mm                                                     pressure will evolve?

2005

1-(a)      Define any three of the following:

                (i)            Moel.                    (ii)           Atomice Mass.                  (iii)          Empirical Formula.

                (iv)         Random Error.   (v)          Limiting Reactant.

    (b)      The molecular mass of a compound is 180 and its empirical formula is CH₂O: find the molecular                       formula.

    (c)       54 gm os dinitrogen pentaoxide (N₂O₅) is decomposed on heating as under.

                2N₂O₅(_S)         ^Heat              4NO₂(_g); find out the volume of NO₂ and O₂ at S.T.P.

    (d)      Fill in the blanks with the correct answers:

                (i)            The significant figure of 5.734 is 4.

                (ii)           The molecular mass of Na₂CO₃ is 106 amu.

                (iii)          64 gm of SO₂ contains 6.023 x 10²³ number of molecules.

                (iv)         The decimal fractional part of logarithm is called Mantica.

                (v)          At sea level and 0⁰C the atmospheric pressure on each square inch of our body is 14.7                                        pounds.

2004

1-(a)      Define the following:

                (i)            Molar Volume.                  (ii)           Stoichiometry.                  (iii)          Significant Figures.

                (iv)         Random Error.

    (b)      The atomic mass of Na = 23 a.m.u.

                (i)            Calculate the mass of 2.408 x 10²³ atoms of Na.

                (ii)           Calculate the number of moles of Na in 4.6 gm.

    (c)       30 gm of limestone (CaCO₃) was heated:

                (i)            Write the equation of the reaction.

                (ii)           Calculate the mass of CO₂ produced.

                (iii)          Calculate the volume of CO₂ at S.T.P.

    (d)      Differentiate between the empirical formula and the molecular formula.