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When we concept that one mole of a subst...

When we concept that one mole of a substance contains the same numbers of elementary entities or one mole of any other substance, we don’t actually need to know what that number is. Sometimes however we will need to work with the actual number of elementary entities in a mole of substance. This number is called Avogadro.s number.
`N_(A)=6.022137xx10^(23)` molecules
The unit `mol^(-1)` which we read as per mole signifies that a collection of `N_(A)` molecular level entities is equivalent to one mole at the macroscopic level. For example a mole of carbon contains `6.02xx10^(23)` atoms of C. A mole of oxygen gas contains `6.02xx10^(23)` molecules of `O_(2)`.
Which of the following is a reasonable value for the numbers of atoms in 1.00 g of helium?

A

`0.25`

B

`4.0`

C

`4.1xx10^(-23)`

D

`1.5xx10^(23)`

Text Solution

Verified by Experts

The correct Answer is:
D
`(1)/(4)` moles = `(1)/(4)xx6xx10^(23)` atoms `= 1.5xx10^(23)`
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When we concept that one mole of a substance contains the same numbers of elementary entities or one mole of any other substance, we don’t actually need to know what that number is. Sometimes however we will need to work with the actual number of elementary entities in a mole of substance. This number is called Avogadro.s number. N_(A)=6.022137xx10^(23) molecules The unit mol^(-1) which we read as per mole signifies that a collection of N_(A) molecular level entities is equivalent to one mole at the macroscopic level. For example a mole of carbon contains 6.02xx10^(23) atoms of C. A mole of oxygen gas contains 6.02xx10^(23) molecules of O_(2) . The number of atoms present in 8 g of ozone is

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