Explaining ortho and para forms of hydrogen

Question

Q1 a) Name the scientists who got Chemistry Nobel prize in 1906 and 1911.

b) Describe Hund’s rule briefly with appropriate example.

c) Write down main features of Mendeleev’s periodic table.

d) What are the factors that affect the ionization energy?

e) Define the following terms

i) Electron affinity

ii) Electronegativity

iii) Van der Waals radius

Question2a) What is the difference between intramolecular and intermolecular hydrogen bonding? Describe with appropriate examples.

b) What are ortho and para forms of hydrogen? Discuss the effect of temperature on ortho and para hydrogens?

c) Describe the following:

i) The alkai metals do not occur in the free state in nature.

ii) The alkali metals are the largest in their corresponding period.

iii) The alkali metals act as strong reducing agent.

d) Discuss briefly anomalous nature of lithium.

Question3)a) Describe the following

i) The alkaline earth metals are soft metals.

ii) The alkaline earth metals are less reactive than alkali metals.

iii) The halides of beryllium polymerise easily.

b) Briefly discuss the complexation behaviour of alkaline earth metals.

c) Why aluminum can not be extracted from aqueous solution of aluminum salts by the process of electrolysis?

d) Why does hot and conc. HNO₃ render Al and Ga passive?

e) Why are the borohydrides more stable than boranes?

Q.4 a) What are metaborates? Give reaction for the borax-bead test for cobalt and the colour obtained thereof.

b) B-N bond distance in borazine is 144 pm, which is less than the sum of single-bond covalent radii of B (82 pm) and N (70 pm). What does this indicate?

c) The inert nature of silicones make them useful for what?

d) What is the structure of most acetylides?

e) Give the reaction of phosphorus with potassium hydroxide.

Question5)a) How is red lead formed from lead oxide? Give the appropriate reactions. What are the uses of red lead?

b) Give appropriate reactions to describe why pale blue liquid of N₂O₃ loses its colour on warming?

c) Hypophosphorous acid is monobasic even though it has three hydrogen atoms. Why?

d) Give one very significant use of hydrazine.

e) What is phosphatic slag?

Question6)a) Describe the paramagnetic behaviour of oxygen on the basis of molecular orbital theory. Give reasons for a large difference in melting and boiling points between oxygen and sulphur.

b) How is peroxomonosulphuric acid prepared from peroxodisulphuric acid and how could two be distinguished from each other? Illustrate with the help of complete reactions.

Question7)a) Enumerate the reasons of delay in the isolation of fluorine. Why is fluorine unable to exhibit positive oxidation states? Describe the strongest ability of this element with the help of Born Haber cycle.

b) Acid strength of oxoacids of halogens increases with increase in the oxidation number of halogen, describe.

c) The interhalogen, ICl₃has a T-shaped structure, explain.

Question8)a) How is the ionisation energy, melting point and boiling point of noble gases affected by their electronic configuration?

b) Describe the structure of XeOF₄ on the basis of VSEPR theory

c) Why do the transition metals exhibit variable oxidation states? How does the stability of oxidation states of transition metals differ across a series and down the group?

Question9)a) Properties of transition metals vary from one element to another, whereas the lanthanide elements resemble one another more close ly and occur together in nature, describe.

b) Why is the range of oxidation states much more restricted in the lanthanide series as compared to the early actinides, describe.

Question10)a) What are the major assumptions of crystal field theory? How does it describe the colours of transition metal complexes?

b) Carbon is theoretically capable of reducing almost all metal oxides at high temperatures, still some metals could not be obtained by reduction of their oxides with carbon, describe.