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प्रश्न
Justify. Element 'X' forms an oxide with the formula X2O3 which is a solid with a high melting point. ‘X’ would most likely be placed in the group of the Periodic Table as Al.
उत्तर
It has 3 electrons in the outermost shell/valency 3 like that of Al.
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संबंधित प्रश्न
An element Y is in second period and group 16 of the periodic table:
(i) Is it a metal or non-metal?
(ii) What is the number of valence electrons in its atom?
(iii) What is its valency?
(iv) What is the name of the element?
(v) What will be the formula of the compound formed by Y with sodium?
A non-metal X which is the largest constituent of air combines with hydrogen when heated in the presence of iron as catalyst to form a gas Y. When gas Y is treated with sulphuric acid, it forms a compound Z which is used as a chemical fertiliser.
(a) What are X, Y and Z?
(b) To which group of periodic table does X belong?
(c) Name the periodic table in which X is placed.
(d) Which element is placed just before X in the period?
(e) Which element is placed just after X in the period?
Two elements X and Y belong to group 1 and 2 respectively in the same period of periodic table. Compare them with respect to:
(i) the number of valence electrons in their atoms
(ii) their valencies
(iii) metallic character
(iv) the sizes of their atoms
(v) the formulae of their oxides
(vi) the formulae of their chlorides
Alkaline earth metals have valency 2. This means that their position in the modern periodic table is in ______.
(a) How is possible valency of an element determined from the electronic configuration of its atom ?
(b) Determine the valency of an element X whose atomic number is 15.
Classify the following elements into Metals and Nonmetals.
S, Mg, Al, P, N, Na.
The basis of the classifications proposed by Dobereiner, Newlands and Mendeleev was ______.
State whether true or false. If false, correct the statement.
Metals can gain electrons.
What is the atomic number of elements of period 3 and group 17 of the Periodic Table?
An element with the atomic number 40 is placed in the period.
