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प्रश्न
In the modern periodic table, the positions of 1 to 20 elements are shown here. Identify the elements A and B. Write their atomic number.
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उत्तर
- Element A is lithium (Li).
Element B is neon (Ne). - Atomic number of element A is 3.
Atomic number of element B is 10.
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संबंधित प्रश्न
The position of three elements A, B and C in the Periodic Table are shown below –
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Group 16
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Group 17
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A
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B
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C
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(a) State whether A is a metal or non-metal.
(b) State whether C is more reactive or less reactive than A.
(c) Will C be larger or smaller in size than B?
(d) Which type of ion, cation or anion, will be formed by element A?
In the Modern Periodic Table, calcium (atomic number 20) is surrounded by elements with atomic numbers 12, 19, 21, and 38. Which of these have physical and chemical properties resembling calcium?
Why do all the elements of the same group have similar properties?
Give two example of group 1 elements.
What is the significance of atomic number in the modern classification of elements? Explain with the help of an example.
where should hydrogen be placed in the modern periodic table? Give reason for your answer.
Name the scientist who prepared modern periodic table.
Which of the following statement is correct in regard to the classification of elements?
(a) Elements in modern periodic table are arranged on the basis of increasing atomic masses.
(b) Elements in Mendeleev's periodic table are arranged on the basis of increasing atomic numbers.
(c) In modern periodic table, the element nickel of lower atomic mass is kept before the element cobalt of higher atomic mass.
(d) In modern periodic table, the isotopes of chlorine having different atomic masses are kept in the same group.
Which of the following statement about the modern periodic table is correct?
(a) It has 18 horizontal rows known as periods.
(b) It has 7 vertical columns known as periods.
(c) It has 18 vertical columns known as groups.
(d) It has 7 horizontal rows known as groups.
Which element has two shells, both of which are completely filled with electrons?
How would the tendency to lose electrons change as we go from left to right across a period of the periodic table?
State whether the following statement is true or false:
On going down in a group of the periodic table, the number of valence electrons increases.
What is the major characteristic of the first elements in the periods of the periodic table? What is the general name of such elements?
What is the usual number of valence electrons and valency of group 18 elements of the periodic table?
What are the merits of the modern periodic table of elements?
What is a group in the periodic table?
Helium and neon are unreactive gases. What, if anything, do their atoms have in common?
What are the advantages of the periodic table?
The atomic numbers of the three elements X, Y and Z are 2, 6 and 10 respectively.
(i) Which two elements belong to the same group?
(ii) Which two elements belong to the same period?
Give reasons for your choice.
How many groups and periods does the modern periodic table have?
State its position in the periodic table?
Write a short note.
Structure of the modern periodic table.
Name and state the following with reference to the elements of the first three periods of the periodic table.
A covalent compound formed by an element in period 2 and a halogen.
Give the symbol and valency of the following element and radical.
Oxygen [Oxide]
Compare Modern Periodic Law with Mendeleev's Periodic Law.
Right or wrong sentence.
To the left of the zig-zag line in the periodic table are the metal elements.
Identify gas A in the following experiment.
The inert gas which lies in the third period is ______
Where would you locate the element with electronic configuration 2,8 in the Modern Periodic Table?
The three elements A, B and C with similar properties have atomic masses X, Y and Z respectively. The mass of Y is approximately equal to the average mass of X and Z. What is such an arrangement of elements called as? Give one example of such a set of elements.
Three elements A, B and C have 3, 4 and 2 electrons respectively in their outermost shell. Give the group number to which they belong in the Modern Periodic Table. Also, give their valencies.
- Write the electronic configuration of element X, given by its symbol as under: \[\ce{^40_20 X}\]
- Determine its position in the modem periodic table.
- What is the nature of its oxide?
- Name one other element of its group.
Name the following metal:
A metal present in period 3, group 1 of the periodic table.
An element has 2 electrons in its N shell.
State its position in periodic table.
Match the atomic number with the following:
An element of group 2.
A group of elements in the periodic table is given below (Boron is the first member of the group and Thallium is the last).
Boron, Aluminium, Gallium, Indium, Thallium
Answer the following question in relation to the above group of elements:
If the electronic configuration of aluminium is 2, 8, 3, how many electrons are there in the outer shell of thallium?
