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What is Avogadro Number ?

What is Avogadro Number :-

Hydrogen and oxygen reacts to form water :
2H₂ + O₂ = 2H₂ O
In this reaction 2 molecules of hydrogen react with one molecule of oxygen to form two molecules of water. The amount of substances taking part in a reaction can be determined easily and their amount can be easily represented by the number of its molecules or atoms. Hence, to make the understanding of the amount of substances, convenient, a new unit ‘mole’ was proposed. According to the mole hypothesis “The mass of one mole of a substance is equal to its gram atomic weight or the gram molecular weight.”
According to this definition :
The weight of 1 mole of the substance
18 gms water (H O) 2
17 gms ammonia (NH )3
44 gms carbon-di-oxide (CO )2
12 gms carbon (C)
24 gms magnesium (Mg)
In one mole of every substance, the number of its particles (atoms, ions, molecules) is definite, which is known as the Avogadro number and its value is 6.022×10²³ . In 18 gms of water there are 6.022×10²³ molecules of water or 6.022×10²³ atoms of oxygen and 2 (6.022×10²³ ) atoms of hydrogen. This has been named in honour of the Italian scientist Amedeo Avogadro.

The basic particles of atom are electron, proton and neutron.
The negatively charged particles in the atom are electrons.
The numeric value of the charge on electron and proton is the same but their sign is opposite.
James Chadwick discovered neutrons.
There are 6.022×10²³ particles in one mole. This is known as the Avogadro number.
The NTP volume of 1 mole of a gas is 22.4 litres.
The formula to determine the maximum number of electrons in a shell is 2n² .
When the atomic number is the same but mass number is different they are known as Isotopes.
Isobars are elements having different atomic number and the same mass number.
There are three isotopes of hydrogen, Protium, Deutirium and Tritium.

1. The Plum Pudding Model of atom was given by:
(a) Neil Bohr
(b) Thomson
(c) Ernest Rutherford
(d) Goldstein

Answer⇒ { B}

2. The discoverer of neutron was :
(a) C.V. Raman
(b) Rutherford
(c) J.J. Thomson
(d) James Chadwick

Answer ⇒ { D}

3. The size of atom is :
(a) 10^-6 cm
(b) 10^-15 cm
(c) 10^-2 cm
(d) 10^-8 cm

Answer ⇒ {D }

4. The number of neutrons in the Deutirium Isotope of hydrogen is /are :
(a) one
(b) Two
(c) Three
(d) Not even one

Answer ⇒ {A }