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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.
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
Fill in the blank:
The modern periodic table consists of ……………. periods.
Name two elements you would expect to show chemical reactions similar to magnesium. What is the basis for your choice?
Write the names given to the vertical columns and horizontal rows in the Modern Periodic Table. How does the metallic character of elements vary on moving down a vertical column? How does the size of atomic radius vary on moving left to right in a horizontal row? Give reason in support of your answer in the above two cases.
Fill in the following blank with suitable word:
The horizontal rows in a periodic table are called ...............
How many periods and groups are there in the long form of periodic table?
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.
How does the chemical reactivity of the halogens vary on going in group 17 of the periodic table?
Explain why All the elements of a period have different chemical properties.
On the basis of electronic configuration, how will you identify chemically similar elements?
What are the merits of the modern periodic table of elements?
Consider the following elements:
20Ca, 8O, 18Ar, 16S, 4Be, 2He
Which of the above elements would you expect to be:
(i) very stable?
(ii) in group 2 of the periodic table?
(iii) in group 16 of the periodic table?
An element X belongs to 3rd period and group 2 of the periodic table. State:
(a) number of valence electrons
(b) valency
(c) metal or non-metal
(d) name of the element
How many groups and periods does the modern periodic table have?
Name two elements in each case: Lanthanides
Name two elements in each case:
Actinides
State its position in the periodic table?
Name an alkali metal in period 3 and halogen in period 2.
Write a short note.
Structure of the modern periodic table.
What is meant in the periodic table by a period?
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.
An element A has 2 electrons in its fourth shell. State its electronic configuration.
In the Modern Periodic Table – atoms of all elements are arranged according to their increasing order of – atomic numbers. An atom of nitrogen has seven protons and seven electrons. State what would be its atomic number.
Give the symbol and valency of the following element and radical.
Oxygen [Oxide]
Give the symbol and valency of the following element and radical.
Bisulphate
Give the chemical formula of sodium hydroxide
Give the chemical formula of sodium bicarbonate
Distinguish between:
Group 17 - Group 18
______ and ______ are called inner transition elements.
Which of the given elements A, B, C, D and E with atomic number 2, 3, 7, 10 and 30 respectively belong to the same period?
The elements A, B, C, D and E have atomic number 9, 11, 17, 12 and 13 respectively. Which pair of elements belong to the same group?
Which of the following is the outermost shell for elements of period 2?
Compare the radii of two species X and Y. Give reasons for your answer.
- X has 12 protons and 12 electrons
- Y has 12 protons and 10 electrons
Noble gases are placed in the ______ group in the modern periodic table.
A part of modern periodic table is given below. On its basis, answer the following questions:
| Group No. → | 1 | 2 | 13 | 14 | 15 | 16 | 17 | 18 |
| Period ↓ | ||||||||
| 2 | A | B | ||||||
| 3 | E | D | F | C |
Which of the element is a Metalloid?
Answer the following in respect of element \[\ce{_16^32S}\].
To which group and period does it belong?
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?
