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Q. General Characteristics of the f-block?
You know that the 14 elements from cerium (Z = 58) to lutetium (Z = 71), which follow lanthanum (Z = 57) in the periodic table, are known as lanthanides, lanthanons or lanthanoids. Note that some authors include lanthanum also in lanthanides, but there IS no general agreement on it. These elements are characterised by successive filling of 4f orbitals in their atoms. These elements along with yttrium and lanthanum were originally known as rare earth elements or simply rare earths. The word 'earth' was used because they occur as oxides, which in early usage meant earth, and the word rare was used because of the great hard in their separation from each other. Otherwise, these are not particularly rare in earth's crust. For illustration, lanthanum, neodymium and cerium are more abundant than lead. Even the scarcest of them, thulium, is as abundant as bismuth and more abundant than arsenic, cadmium, selenium, or mercury none of which is usually considered rare.
The fourteen elements from thorium (Z = 90) to lawrencium (2 = 103) following actinium in the periodic table are define as actinides, actinoids or actions. They are analogous to the lanthanides and result from the filling of the of orbitals as the lanthanides result from the filling of 4f orbitals. Prior to 1940, only the obviously occurring actinides, i.e., thorium, protactinium and uranium were known. The remaining actinides have been produced artificially since then and are collectively define as transuranium elements.
Q. Define Food spoilage? Food spoilage is a major concern of all people. Spoilage by growth of bacteria, yeasts and moulds limits the time that the food can be stored and still
Illustrate ib brief about the Single crystal growth Single crystals are grown either by Czochralski (CZ) method or by Float Zone (FZ) method. It comprises a furnace with a gra
Drying - Chemical Properties of oils and fats Some fixed type of oils, containing glycerides of unsaturated fatty acids comprising two or three double bonds have the trend of s
Preservatives: The preservatives avoid spoilage of food because of microbial expansion. The most common preservative employed is sodium benzoate; C 6 H 5 COON a It is metabol
The nucleus of the element 21 E 45 contains: (1) 45 protons and 21 neutrons (2) 21 protons and 24 neutrons (3) 21 protons and 45 neutrons (4) 24 protons and 21 n
zinc+copper(ll) chloride
Q. What is law of definite proportions? A given compound is forever composed of the same elements in the same proportion by mass. This fact is recognized as the law of definit
what is the balanced equation of the burning of an unknown hydrocarbon, C4H9 in air
The transition metal complexes are known to be paramagnetic in character. CFT helps us to understand the magnetic properties in terms of magnetic susceptibility measurements. The m
advantages and dis advantages?
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