Chemistry Notes 2nd Year Chap 4

                                   Important Question 

Q1 Give the uses of  H2SO4

Ans:  It is used in manufacturing of fertilizers like (NH4)2SO4 Calcium superphosphate
             In the refining of petroleum to remove nitrogen and Super compounds.
                 In the manufacture of HCl HPO4 HNO3 and sulphate.
              As dehydrating agent
              In textile iron steel leather and paper industries

Q2 Give reaction of PCl3 with Alcohol and carboxylic acid.

Ans: PCl3+ 3CH3OH----------> 3CH3Cl+ H3PO3
         PCl3+ 3CH3COOH----------> 3CH3COCl+H3PO3

Q3 Give two reactions for the preparation of phosphorus acid

Ans: It prepared by dissolving phosphorus Trioxide  in cold water
           P2O3+3H2O--------> 2H3PO3
           Its obtained by hydrolysis of phosphorus trichloride
PCl3+3H2O--------> H3PO3+ 3HCl

Q4 Give the name of four elements that do not react with HNO3

Ans:  HNO3 do not react with Gold, Platinum iridium and titanium

Q5  Justify that NO acts as an oxidizing agent

Ans:  NO oxidizes SO2 to H2SO4 it oxidizes H2SO3 to H2SO4 and H2S to S
                           
2NO+SO2+H2O---------> H2SO4 + NO2
H2S+2NO-------------> H2O+S+N2O
H2SO3+2NO---------> H2SO4+N2O

Q6   What is meant by fuming nitric acid.

Ans: Concentrated HNO3 is a colourless volatile liquid and it fumes strongly in the air releasing the NO2 gas it is called fuming nitric acid.

Q7  Describe the ring test for the confimation  of presence of nitrate ions is slotion.

Ans:  The ring test performed for the confirmation NO3-1 in the aqueous solution. To the salt solution add freshly prepared solution of FeSO4. Then add few drops of concentrated H2SO4 along the side of the test tube. A brown ring is produced at the junction of two liquid and this ring has the composition FeSO4.NO

Q8 Why does aqua regia dissolve gold and platinum? Also write the reaction with Gold.

  Ans: When aqua regia is prepared by mixing the one volume of HNO3 and 3 volume of concentrated HCl. It is employed to dissolve the gold and platinum.


Q9 Name the three allotropic Phosphorus

Ans: Phosphorus in three allotropic forms as give below

              White Phosphorus, Red Phosphorus, and Black Phosphorus

Q10 Write four dissimilarities b/t Oxygen and Sulphur.

Ans: Oxygen have two allotropic forms O2&O3 whereas sulphur has three rhombic, monoclinic and plastic.
           Oxygen is a gas while sulphur is solid at room temprature.
             Oxygen sparingly soluble in water while sulphur is insoluble in water.
                 Oxygen is paramagnetic and sulphur is diamagnetic in nature.

Q11 Write four similarities b/t Oxygen and Sulphur.

Ans: Both has same outer electronic configuration.
            Both are usually divalent.
               Both exhibit the allotropic forms.
                  Both are non-metals.

Q12  What is laughing gas ? Why is it called so ?

Ans: Dinitrogen oxide is colourless gas with a faint, pleasant smell ad a sweetish taste. It is fairly soluble in cold water. Its mixture with little water. Its mixture with little water if inhaled for sufficiently long time produces hysterical laughter, hence it is also knon as laughing gas.

Q13 Why the elements of group VI-A other than Oxygen show more than two oxidation state.

Ans: All the atoms of group IV-a except Oxygen show a covalency of +2 +4 and +6 oxidation state is given due to two unpaired electrons in the valance shell. +4 Oxidation state is give when one electron from p-orbital os promoted to next vacant d-orbital while +6  state is given when anothe electron is promoted to the next vacant d-orbital.

Q14 Give Examples of two important oxyacids of nitrogen while giving their sutructures.
Q15  Write structural formulas of NO,N2O3,N2O3N2O