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प्रश्न
Name the unit in which the radius of an atom is usually expressed.
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उत्तर
The radius of an atom is usually expressed in nanometre (nm).
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संबंधित प्रश्न
The average atomic mass of a sample of an element X is 16.2 u. What are the percentages of isotopes `""_8^16X" and """_8^18X` in the sample?
Tick the most appropriate answer.
Who discovered that radioactive rays are given out by uranium?
- Henri Becquerel
- Marie Curie
- Pierre Curie
- Schmidt
WRITE SHORT ANSWER
Name three inert gases.
Give the charge and the mass of an electron, proton and neutron present in an atom ?
What are orbits or shells ?
Name three non-metals/radicals which have valency -1, -2, and -3.
What does the word ‘atom’ mean?
What is an atom ? How do atoms usually exist ?
The electronic configuration of an element Z is 2, 8, 8.
(a) What is the atomic number of the element?
(b) State whether element Z is a metal or a non-metal.
(c) What type of ion (if any) will be formed by an atom of element Z? Why?
(d) What is special about the outermost electron shell of the atom of this element?
(e) Give the name and symbol of element Z.
(f) Name the group of elements to which Z belongs.
Match the pairs.
| Group 'A' | Group 'B' |
| a. Proton | i. Negatively charged |
| b. Electron | ii. Neutral |
| c. Neutron | iii. Positively charged |
Elements X and Y have 1 and 7 electrons in their outermost shell respectively.
What will be the charge present of the molecule XY after chemical combination?
Select the correct answer to the statement given below:
The basic unit of matter is not capable of independent existence.
Rewrite the given sentence in correct form.
Elements contain two or more kind of atoms and compounds contain only one kind of atom.
The basic unit of matter is ______.
The smaller particles found in the atom is called ______.
An atom of an element has no electron. Will that atom have any mass or not? Can an atom exist without electron? If so then give example.
Project.
To have an idea of what atoms are, students can be asked to construct atoms using pipe cleaners (thin metal wires-electron shells), pompoms (balls-different colours for protons and neutrons) and beads (electrons). Students will love and enjoy putting them together and they look great hanging from the ceiling in the classroom.
Define the following term with an example.
Non-metal
Define the term ions or radicals.
