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प्रश्न
Mention briefly the salient features of Dalton’s atomic theory (five points)
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उत्तर
Salient features of Dalton’s atomic theory:
- Matter consists of very small and indivisible particles called atoms, which can neither be created nor can be destroyed.
- The atoms of an element are alike in all respects i.e. size, mass, density, chemical properties but they differ from the atoms of other elements.
- Atoms of an element combine in small numbers to form molecules of the element.
- Atoms of one element combine with atoms of another element in simple whole number ratio to form molecules of compounds.
- Atoms are the smallest units of matter that can take part in a chemical reaction during which only rearrangement of atoms takes place
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संबंधित प्रश्न
Fill in the blank
Neutrons are .......................... particles having mass equal to that of protons.
Give the following a suitable word/phrase.
The sum of the number of protons and neutrons of an atom.
FILL IN THE BLANK
In an atom, the last shell containing electrons is called its..................shell.
Tick the most appropriate answer.
Which of the following scientists observed that cathode rays consists of negatively charged particles?
- John Dalton
- J J Thomson
- James Chadwick
- Democritus
Tick the most appropriate answer.
In 1908, R A Millikan found the charge of an electron to be
- 1.6 x 10-19 C
- 1.6 x 10-15 C
- 1.4 x 10-19 C
- 1.6 x 19-16 C.
State whether the following statement is true or false :
The anode rays obtained from all the gases consist of positively charged particles called protons.
Compare an electron and a proton in respect of mass and charge.
Define the term Nucleons.
Explain in brief – Goldstein’s experiment which led to the discovery of the proton.
Select the correct answer from the choice in the bracket to complete the sentence:
Magnesium atom with electronic configuration 2, 8, 2 achieves stable electronic configuration by losing two electrons, thereby achieving stable electronic configuration of the nearest noble gas _______.
