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प्रश्न
Define the following term with an example.
Element
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उत्तर
Element: It is a substance that cannot be broken down into simpler substance by chemical means
Ex.: Oxygen, Hydrogen, Gold & Helium.
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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?
TRUE \ FALSE
Elements having a tendency to accept electrons are called metals
WRITE SHORT ANSWER
Define an ionic compound.
Write the names of the elements present in the:-
Sodium hydroxide
Write the names of the elements present in the:-
Acetic acid
Write the names of `"Ca"("NO"_3)_2` compounds :
What is the maximum number of electrons present in:
1. first shell
2. second shell
3. third shell and
4. fourth shell
State Dalton’s atomic theory.
How did Neils Bohr visualise the atom ?
Name the particle or particles you would expect to find in :
The orbit of an atom
State two observations which show that atom is not indivisible.
What is an atom ? How do atoms usually exist ?
For the symbols H, D and T, write the subatomic particles (protons, neutrons and electrons) found in each one of them.
Match the pairs.
| Group 'A' | Group 'B' |
| a. Proton | i. Negatively charged |
| b. Electron | ii. Neutral |
| c. Neutron | iii. Positively charged |
What is the contribution of the following in atomic structure?
Maharshi Kanada
A radical take part – unsplit in a chemical reaction and retains its identity in reactions.
With reference to the radical –
- ammonium
- bisulphate
- carbonate
state the group of atoms present in each radical.
Select the correct answer to the statement given below:
The smallest particle of a substance – capable of independent existence and which retains the characteristics of the substance.
The smallest particle of matter that can exist by itself is ______.
Draw the structure of an atom and explain the position of the sub-atomic particles.
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.
Define the following term with an example.
Metalloid
Atoms of different elements having the same number of ______ are called isotones.
The number of atoms present in a molecule is called its ______.
A sample of vitamic C is known to contain 2.58 ×1024 oxygen atoms. How many moles of oxygen atoms are present in the sample?
