Wednesday, 22 January 2020

PLUS ONE CHEMISTRY QUESTIONS

Chemistry is the science of molecules and their transformation.It is deals with the composition, structure and properties of matter
Chapter 1,
          SOME BASIC CONCEPTS 
Important questions ,

1.state and illustrated the low of multiple         proportion
2.calcualte the amound of CO2(g)produced       by the reaction of 32g of CH4 (g) and 32g          of O2(g)
3.The number of oxygen atoms present in 5      moles of glucose (C6H12O6)is ......?
4.find the molecular formula of the                     combound with molar mass 78g 1/mol and     empirical formula CH
5.calculate the mass of oxalic acid                       dehydrate  [H2C2O4.2H2O] required  to           prepare 0.1M,250ml  of its aqueous                 solution
6.NO and NO2 are two oxide of nitrogen
    (a) state the low and which is the low of          chemical combination is illustrated by            these compounds
7.(a) Determine the number of moles                  present in 0.55 mg of electrons
   i)1 mole ii) 2 moles iii)1.5 moles iv) 0.5              moles
   (b) two elements carbons and hydrogen          combine to form C2H6,C2H4 and C2H2            identify the law illustrate here
8. Empirical formula represents the simple        whole number ratio of various atoms              present in a compound
   (a) given the relation between empirical          formula and molecular formula
   (b)An organic compound has the                       following percentage composition                   C=12.36% H=2.13% H=2.13% Br=85% Its         vapours density is 94 . Find its molecular       formula?
   (c) what is the mole fraction?
9.Hydrogen combines  with hydrogen to           form  two different  compound  namely         water (H2O) and hydrogen  peroxide               (H2O2)
   (a) which law is obeyed by this                         combination ?
   (b)state the law?
   (c) How many significant figur are present     in following
         i)0.0025         ii)285
10.A given compound alwys contain with          exactly the same proportion of elements        by weight
    (a) (i)Name the above low
          (ii)write the name of the scientist who                 proposed law
    (b) calculate the number of molecule in                each of the following
          (i) 1g N2 (ii) 1g CO2
           Molecular mass of N2=28 and CO2=44
11.howmany moles of dioxygen are present        in 64g of dioxygen ?
12.Calculate the number of moles of oxygen        required to produce 240g of MgO by                burning Mg metals ?(atomic mass                    Mg=24,O=16)
13.If the mass percent of various element of       a compound is known, its empirical                 formula can be calculated
     (a)what is mass percent?
     (b)Compound  contain  4.07% Hydrogen,         24.27%carbon and 71.65% chlorine
     Its molecular mass is 98.96 what are the         empirical and molicular formula ?
14.One mole is the amound of substance              that  contain as many particles as 12 g of
      C12  is isotope of carbon
     (a) what di you mean by molar mass of           compound ?
     (b)Calculate the number of moles in 1L of
      Water?
15.The law of chemical combination are the       basis of atomic theory
    (a)Name the law of chemical                              combination  illustrated  by the pair of            compound CO and CO2
    (b)State and explain the law of                          conservation  of mass



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