Answer:
2.04 x 10²⁴ molecules
Explanation:
Given parameters:
Mass of Be(OH)₂ = 145.5g
To calculate the number of molecules in this mass of Be(OH)₂ we follow the following steps:
>> Calculate the number of moles first using the formula below:
Number of moles = mass/molarmass
Since we have been given the mass, let us derive the molar mass of Be(OH)₂
Atomic mass of Be = 9g
O = 16g
H = 1g
Molar Mass = 9 + 2(16 + 1)
= 9 + 34
= 43g/mol
Number of moles = 145.5/43 = 3.38mol
>>> We know that a mole is the amount of substance that contains Avogadro’s number of particles. The particles can be atoms, molecules, particles etc. Therefore we use the expression below to determine the number of molecules in 3.38mol of Be(OH)₂:
Number of
molecules= number of moles x 6.02 x 10²³
Number of molecules= 3.38 x 6.02 x 10²³
= 20.37 x 10²³ molecules
= 2.04 x 10²⁴ molecules
1. <span>Count Sergei Lvovich Levitsky invented the Bellows camera. The correct option among all the options that are given in the question is the last option or option "D".
2. The substance with which the first photograph was made from, was Bitumen. The correct option among all the options given in the question is the first option or option "A".
3. Kodak DCS 100 was the first commercially available digital camera. The correct option among all the options that are given in the question is the first option or option "A".</span>
Answer:
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They are not always identical because they have different isotope numbers which develops different neutrons numbers
