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प्रश्न
Which of the following have inert gases 2 electrons in the outermost shell.
विकल्प
He
Ne
Ar
Kr
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उत्तर
He
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संबंधित प्रश्न
An element P (atomic number 20) reacts with an element Q (atomic number 17) to form a compound. Answer the following questions giving reason:
Write the position of P and Q in the Modern Periodic Table and the molecular formula of the compound formed when P reacts with Q.
Rewrite the following statement after correction, if necessary:
Periods are the horizontal rows of elements.
Rewrite the following statement after correction, if necessary:
Isotopes are the elements of the same group.
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
Rearrange the columns 2 and 3 so as to match with the column 1.
| Column 1 | Column 2 | Column 3 |
| i. Triad ii. Octave iii. Atomic number iv. Period v. Nucleus vi. Electron |
a. Lightest and negatively charged particle in all the atoms b. Concentrated mass and positive charge c. Average of the first and the third atomic mass d. Properties of the eighth element similar to the first e. Positive charge on the nucleus f. Sequential change in molecular formulae |
1.Mendeleev
2. Thomson
3. Newlands
4. Rutherford
5. Dobereiner
. Moseley
|
Choose the correct option and rewrite the statement.
The number of electrons in the outermost shell of alkali metals is _______.
Which one of the following statements is not correct about the trends in the properties of the elements of a period on going from left to right?
The atom of an element has electronic configuration 2, 8, 7. To which of the following elements would it be chemically similar?
Identify and name the metals out of the following elements whose electronic configurations are given below.
- 2, 8, 2
- 2, 8, 1
- 2, 8, 7
- 2, 1
Complete the following cross word puzzle
Across:
(1) An element with atomic number 12.
(3) Metal used in making cans and member of Group 14.
(4) A lustrous non-metal which has 7 electrons in its outermost shell.
Down:
(2) Highly reactive and soft metal which imparts yellow colour when subjected to flame and is kept in kerosene.
(5) The first element of second Period
(6) An element which is used in making fluorescent bulbs and is second member of Group 18 in the Modern Periodic Table
(7) A radioactive element which is the last member of halogen family.
(8) Metal which is an important constituent of steel and forms rust when exposed to moist air.
(9) The first metalloid in Modern Periodic Table whose fibres are used in making bullet-proof vests
