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In the following table six elements A, B, C, D, E and F here letters are not the usual symbols of the elements
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1
|
5248
|
April 1, 2019
|
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1. Which two criteria did Mendeleev use to classify the elements in his periodic table?
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1
|
8721
|
April 1, 2019
|
|
1. Why do we classify elements?
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1
|
785
|
April 1, 2019
|
|
On the basis of Mendeleev’s Periodic Table given below, answer the questions that follow the table:
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1
|
5659
|
April 1, 2019
|
|
Atomic number is considered to be more appropriate parameter than atomic mass for classification of elements in periodic table. Why?
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1
|
750
|
April 1, 2019
|
|
The atomic number of an element X is 12
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1
|
738
|
April 1, 2019
|
|
What is periodicity in properties of elements with reference to the modern periodic table?
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1
|
872
|
April 1, 2019
|
|
Na, Mg and Al are the elements of the 3rd period of the Modern Periodic Table having group;
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1
|
1493
|
April 1, 2019
|
|
Write the number of periods and groups in the Modern Periodic Table
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1
|
603
|
April 1, 2019
|
|
An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound
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1
|
1138
|
April 1, 2019
|
|
Write the names given to the vertical columns and horizontal rows in the modern periodic table
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|
1
|
1953
|
April 1, 2019
|
|
An element 'X' belong to 3rd period and group 13 of the modern periodic table
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|
1
|
1934
|
April 1, 2019
|
|
An element ‘X’ (Atomic number - 20) burns in the presence of oxygen to form a basic oxide
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|
1
|
4271
|
April 1, 2019
|
|
Calcium is an element with atomic number 20. Stating reason, answer each of the following questions:
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1
|
620
|
April 1, 2019
|
|
An element ‘X’ is placed in the 3rd period of the modern periodic table
|
|
1
|
2378
|
April 1, 2019
|
|
The atomic number of an element ‘X’ is 20
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|
1
|
1163
|
April 1, 2019
|
|
Given below are some elements of the modern periodic table, atomic, number of the element is given in the parentheses
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|
1
|
1979
|
April 1, 2019
|
|
The elements 4Be, 12Mg and 20Ca, each having two valence electrons, in their valence shells, are in period 2, 3 and 4 respectively
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|
1
|
701
|
April 1, 2019
|
|
Write the number of periods the modern periodic table has. State the changes in valency and metallic character of elements
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1
|
2025
|
April 1, 2019
|
|
From the following elements: 4Be , 9F , igK , 20Ca
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|
1
|
701
|
April 1, 2019
|
|
The electronic configuration of an element is 2, 8, 8, 1
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|
1
|
2875
|
April 1, 2019
|
|
The elements Be, Mg and Ca each having two electrons in their outermost shells are in periods 2, 3, and 4 respectively
|
|
1
|
575
|
April 1, 2019
|
|
Consider two elements 'X' (Atomic number 17) and 'Y' (Atomic number 20)
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|
1
|
1377
|
April 1, 2019
|
|
The electrons in the atoms of four elements A, B, C and D are distributed in three shells having, 3, 5 and 7 electrons in the outermost shell respectively
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|
1
|
1543
|
April 1, 2019
|
|
Study the following table in which positions of six elements A, B, C, D, E and F are shown as they are in the modern periodic table:
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|
1
|
627
|
March 30, 2019
|
|
What is meant by ‘group’ in the modern periodic table? How do the following change on moving from top of bottom in a group?
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|
1
|
2236
|
March 30, 2019
|
|
Consider two elements ‘A’ (Atomic number 17) and ‘B’ (Atomic number 19)
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1
|
2344
|
March 30, 2019
|
|
Define the following terms: a. (i) Valency (ii) Atomic size
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1
|
4889
|
March 30, 2019
|
|
Based on the group valency of elements. State the formula for the following giving justification for each:
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|
1
|
941
|
March 30, 2019
|
|
An element X (atomic number 17) reacts with an element Y (atomic number 20) to form a compound
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|
1
|
821
|
March 30, 2019
|