Question

Which of the following have same no. of mole as 20g of calcium.
1)24g mg
2)12g Carbon
3) 8g oxygen gas
4)16 g oxygen atom
Please answer with explanation. don't post irrelevant answer​

Answer 1

Explanation:

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Answer 2

We know that :-

$\rm \boxed{\rm n = \frac{M}{W} } \\ \\ \rm where \: M = given \: mass\\ \rm \:W = molar \: mass$

Now , first we will find out number of moles in 20 g of calcium.

Molar mass of calcium = 40 u

$\rm n = \dfrac{20}{40} \\ \\ \rm \rightarrow n = \dfrac{1}{2} = 0.5 \: mol$

Now , we will check each option one by one.

1. 24g mg

Atomic mass of mg = 24 u

$\rm n = \dfrac{24}{24} \\ \\ \rm \rightarrow n = 1 \: mol$

Therefore, option (1) is incorrect because didn't get number of moles as 0.5 mol.

2. 12 g carbon

Atomic mass of carbon = 12 u

$\rm n = \dfrac{12}{12} \\ \\ \rm \rightarrow n = 1 \: mol$

Therefore, option (2) is incorrect because didn't get number of moles as 0.5 mol.

3. 8g oxygen gas

Molar mass of oxygen gas ( O2) = 32 u [ 2× 16 = 32]

$\rm n = \dfrac{8}{32} \\ \\ \rm \rightarrow n = \dfrac{1}{4} \: mol$

Therefore, option (3) is incorrect because didn't get number of moles as 0.5 mol.

4. 16 g oxygen atom

Atomic mass of oxygen = 16 u

$\rm n = \dfrac{16}{16} \\ \\ \rm \rightarrow n = 1 \: mol$

Therefore, option (4) is incorrect because didn't get number of moles as 0.5 mol.