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प्रश्न
Give scientific reason.
All the mass of an atom is concentrated in the nucleus.
उत्तर
All the mass of an atom is concentrated in the nucleus because the atom contains three subatomic particles like electron, proton and neutron. Out of which, the nucleus present at the centre of an atom contains two subatomic particles that are protons and neutrons, and the mass of the nucleus is the sum of the mass of protons and neutrons located at the centre of an atom.
संबंधित प्रश्न
Tick the most appropriate answer.
Who discovered that radioactive rays are given out by uranium?
- Henri Becquerel
- Marie Curie
- Pierre Curie
- Schmidt
TRUE \ FALSE
Elements combine in definite proportions to form compounds.
TRUE \ FALSE
Cathode rays are a stream of fast moving particles that travel in random directions.
ANSWER IN DETAIL
State the postulates of the Dalton’s atomic theory.
Define:- Atom
Define:- Molecule
Define: Relative atomic mass
Give two examples for each of ionic and covalent bond.
What does the word ‘atom’ mean?
How did Neils Bohr visualise the atom ?
Fill in the blank
An excess of electrons produces a ________ charge.
The electron shell ______ is nearest to the nucleus.
Match the pairs.
| Group 'A' | Group 'B' |
| a. Proton | i. Negatively charged |
| b. Electron | ii. Neutral |
| c. Neutron | iii. Positively charged |
In what respects do the three isotopes of hydrogen differ? Give their structures.
Draw the electron dot structure of this compound.
Name the gas that.
Turns moist starch iodide paper blue black.
The basic unit of matter is ______.
State true or false. If false, correct the statement.
The basic unit of an element is molecule.
The number of atoms present in a molecule is called its ______.
Give the salient features of “Modern atomic theory”.
