Short Answer TypeDistinguish between paramagnetism and ferro-magnetism. How does ferro magnetism arise?
Paramagnetism: Paramagnetic substances are weakly attracted by a magnetic field. They are magnetised in a magnetic field in the same direction. They lose their magnetism in the absence of magnetic field. Paramagnetism is due to presence of one or more unpaired electrons which are attracted by the magnetic field. O2, Cu2+, Fe3+, Cr3+ are some examples of such substances.
Ferromagnetism: A few substances like iron, cobalt, nickel, gadolinium and CrO2 are attracted very strongly by a magnetic field. Such substances are called ferromagnetic substances.
Besides strong attractions, these substances can be permanently magnetised. In solid state, the metal ions of ferromagnetic substances are grouped together into small regions called
domains. Thus, each domain acts as a tiny magnet. In an unmagnetised piece of a ferromagnetic substance the domains
are randomly oriented and their magnetic moments get cancelled. When the substance is placed in a magnetic field all the domains
get oriented in the direction of the magnetic field and a strong magnetic effect is produced. This ordering of domains persist even when the magnetic field is removed and the ferromagnetic substance becomes a permanent magnet.
Long Answer Type(i) Breifly explain the physical properties of lanthanoids.
(ii) The chemical reactivity of lanthanoids resembles to which other elements of the periodic table.
Short Answer TypeHow does the acidified KMnO4 react with the following:
(a) Iron(II) solution, (b)SO32–, (c) Iodide (I–) ion, (d) oxalic acid, (e) NO2– (Nitrite ion).
Long Answer TypeExplain any one of following statement:
(i) The transition metals are well known for the formation of interstitial compounds.
(ii) The largest number of oxidation states are exhibited by mangnese in the first series of transition elements.
Short Answer TypeAnswer the following questions:
(i) Which element in the first series of transition elements does not exhibit variable oxidation states and why?
(ii) Why do actinoids in general exhibit a greater range of oxidation states than the Lanthanoids?
Long Answer Typei)Describe how potassium permanganate is made from pyrolusite. Write the chemical equations for the involved reactions.
ii) Describe with an example each of the oxidising actions of permanganate ion in alkaline and acidic media. What acid and alkali are usually used?
Describe how potassium dichromate is made from chromate ore and give the equations for the chemical reactions involved.
Write balanced ionic equations for reacting ions to represent the action of acidified potassium dichromate solution on:
(a) Potassium iodide solution.
(b) Acidified ferrous sulphate solution. Write two uses of potassium dichromate.
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