Make note of it and learn from her mistakes :)
(2) Mg, Ca, and Ba have the most similar chemical properties, and we know this because of their coexistence in the group alkali earth metals (group 2) on the periodic table.
Answer:
78.3 × 10²³ atoms of helium are present in 52 g.
Explanation:
Given data:
Mass of He = 52 g
Number of atoms = ?
Solution:
First of all we will calculate the number of moles of He
Number of moles = mass /molar mass
Number of moles = 52 g/ 4 g/mol
Number of moles = 13 mol
The given problem will solve by using Avogadro number.
It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.
The number 6.022 × 10²³ is called Avogadro number.
For example,
1 mole = 6.022 × 10²³ atoms of helium
13 mol × 6.022 × 10²³ atoms of helium / 1 mole
78.3 × 10²³ atoms of helium
