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प्रश्न
Fill in the blank and rewrite the completed statement:
________ group in the periodic table contains elements that are all gases at room temperature.
उत्तर
The 18th group in the periodic table contains elements that are all gases at room temperature.
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संबंधित प्रश्न
The atomic masses of three elements A, B and C having similar chemical properties are 7, 23 and 39, respectively.
- Calculate the average atomic mass of elements A and C.
- Compare the average atomic mass with atomic mass of B.
- What could the elements A, B and C be?
The elements 4Be, 12Mg and 20Ca, each having two valence electrons in their valence shells, are in periods 2, 3 and 4 respectively of the modern periodic table. Answer the following questions associated with these elements, giving reason in each case:
(a) In which group should they be?
(b) Which one of them is least reactive?
(c) Which one of them has the largest atomic size?
The electrons in the atoms of four elements A, B, C and D are distributed in three shells having 1, 3, 5 and 7 electrons in the outermost shell respectively. State the period in which these elements can be placed in the modern periodic table. Write the electronic configuration of the atoms of A and D and the molecular formula of the compound formed when A and D combine.
Write the atomic numbers of two elements 'X' and 'Y' having electronic configuration 2, 8, 2 and 2, 8, 6 respectively.
Write the number of horizontal rows in the modern periodic table. What are these rows called?
Which element has a total of two shells, with three electrons in its valence shell?
An element with the atomic number 19 will most likely combine chemically with the element whose atomic number is ______.
Use the letters only written in the Periodic Table given below to answer the questions that Follow :
1) State the number of valence electrons in atom J.
2) Which element shown forms ions with a single negative charge?
3)Which metallic element is more reactive than R?
4) Which element has its electrons arranged in four shells?
In the following set of element, one element does not belong to the set. Select this element and state why it does not belong:
Calcium, Magnesium, Sodium, Beryllium
How does the number of valence electrons vary on moving from left or right in the second period of the periodic table?
State one reason for keeping fluorine and chlorine in the same of the periodic table.
In which part of a group would you separately expect the elements to have the greatest metallic character
Explain why, the properties of elements are repeated after 2, 8, 18 and 32 elements in the periodic table.
Which of the following element would lose an electron easily?
(a) Mg
(b) Na
(c) K
(d) Ca
The atomic numbers of the elements Na, Mg, K and Ca are 11, 12, 19 and 20 respectively. The element having the largest atomic radius is:
(a) Mg
(b) Na
(c) K
(d) Ca
On moving from left to right in a period of the periodic table, the atomic number of elements increases. What happens to the size of atoms of elements on moving from left to right in a period?
(a) increases
(b) decreases
(c) remain the same
(d) first increases then decreases
Which of the following set of elements is written correctly in the order of their increasing metallic character?
(a) Mg, Al, Si
(b) C, O, N
(c) Na, Li, K
(d) Be, Mg, Ca
What do you understand by periodicity?
What do you understand by orbits?
How does the number of:
valency vary on moving from left to right in the second period of the periodic table?
An element barium has atomic number 56. Look up its position in the periodic table and answer the following question.
Is it more or less reactive than calcium?
Name the element which has the electronic configuration 2, 8, 3?
In the following table, the positions of six elements A, B, C, D, E and F are given as they are in the Modern Periodic Table :
 |
1 | 2 | 3-12 | 13 | 14 | 15 | 16 | 17 | 18 |
| 2 | A | B | C | D | |||||
| 3 | E | F |
On the basis of the above table, answer the following questions :
(i) Name the element which forms only covalent compounds.
(ii) Name the element which is a metal with valency three.
(iii) Name the element which is a non-metal with valency three.
(iv) Out of B and C, whose atomic radius is bigger and why ?
(v) Write the common name for the family to which the elements D and F belong.
What will be the valency of an element of atomic number 9 (nine)?
Select the correct answer
Identify the metalloid
Parts (i) to (v) refer to changes in the properties of elements on moving from left to right across a period of the periodic table. For each property, choose the letter corresponding to the correct answer from the choices (a), (b), (c) and (d).
(i) The non metallic character of the elements:
(a) Decreases
(b) Increases
(c) Remains the same
(d) Depends on the period
(ii) The electro negativity
(a) Depends on the number of valence electrons
(b) Remains the same
(c) Decreases
(d) Increases
(iii) The ionization potential
(a) Goes up and down
(b) Decreases
(c) Increases
(d) Remains the same
(iv) The atomic size
(a) Decreases
(b) Increases
(c) Remains the same
(d) Sometimes increases and sometimes decreases
(v) The electron affinity of the elements in groups 1 to 7:
(a) Goes up and down
(b) Decreases and then increases
(c) Increases
(d) decreases
The following questions refer to the Periodic Table.
What is the common feature of the electronic configurations of the elements in group 7?
Give the number of the group and the period of elements having three shells with three electrons in valence shell.
In the above table, H does not represent hydrogen.Some elements are given in their own symbol and position in the periodic table while others are shown with a letter. With refrence to the table answer the following questions.
1. Identify the most electronegative element.
2. Identify the most reactive element of Group I.
3. Identify the element from Period 3 with least atomic size.
4. How many valence electrons are present in Q?
5. Which element from group 2 would have the least ionisation energy?
6. Identify the noble gas of the fourth period.
7. In the compound between A and H, what type of bond would be formed and give its molecular formula.
The elements of one short period of the periodic table are given below in order from left to right:
| Li | Be | B | C | O | F | Ne |
Place the three elements fluorine, beryllium and nitrogen in the order of increasing electronegativity.
The elements of one short period of the periodic table are given below in order from left to right:
| Li | Be | B | C | O | F | Ne |
Which one of the above elements belongs to the halogen series?
Moving down in the second group, number of valence electrons ______.
An element A has 2 electrons in its fourth shell. State:
is it a metal or non-metal
An element A has 2 electrons in its fourth shell. State:
is it an oxidising or reducing agent
The electronic configuration of an element is 2, 8, 4. State it:
name and write its one physical property.
State the property trends in general of elements on moving down in a group of the periodic table.
Name or state following with reference to the elements of the first three periods of the periodic table.
A metalloid in period 2 and in period 3.
Name or state following with reference to the element of the first three periods of the periodic table.
The valency of elements in group 1 [I–A].
Chlorine in the Periodic Table is surrounded by the elements with atomic number 9, 16, 18 and 35.
Which of these have Physical and Chemical properties resembling chlorine?
There are three elements E, F, G with atomic numbers 19, 8 and 17 respectively.
Classify the above elements as metals and non-metals.
