Chemistry - 9 Chapter - 4
Periodicity of Elements and Periodic Table
Test - 12

1. Why certain gases are called noble gases? Short..Answer............................................................
In the beginning these gases are named rare gases because they are present in very small amounts in the air. Since they do not reacts with other elements, so these were termed as inert gases. In 1962 some of the compounds on xenon gas were prepared. Hence their name was changed to gases


2. Define Modern Periodic Law?
Short..Answer…………………………………………


3. Each horizontal row at the bottom of modern periodic table contains ________ elements.




4. Elements in modern periodic table have been arranged in ___________?




5. f-Block elements in the modern periodic table are called __________ and __________.



6. Fourth and fifth periods of modern periodic table contain __________ elements each.




7. How will the Modern periodic Table be disturbed if isotopes of an element are discovered now? Short..Answer............................................................
Discovery of new isotopes of an element will not disturb the periodic table because modern periodic table is based on atomic number. Isotopes are atoms of same element having same atomic number but different mass number. So atomic ------ does not change.


8. In how many blocks, elements are divided in modern periodic table?
Short..Answer…………………………………………..
In the modern periodic table, elements have been divided into four blocks, s, p, d and f. The elements present in s and p blocks are called normal elements, whereas the elements present in f and -------- are called transition elements.


9. In the modern periodic table, elements have been divided into six blocks.


10. Is the element having 3 shells and 6 electrons in outer most shell a metal or a non-metal?




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