Question

Which of the following contain same number of atoms- as 20g of calcium
A)24g magnesium
B) 12g carbon
C) 8g Oxygen gas
D) 16g Oxygen atom​

Answer 1

Answer:

$number \: of \: atoms = number \: of \: moles(n) \times avagdro \: \: number \:$

no. of atoms of Ca=( n)× avagdro number

= [(given mass)/ molar mass of Ca] × 6.023× 10^23

= (20/40) × 6.023×10^23

= 0.5× 6.023× 10^23

= 3.011×10^23__________________eq1

a) 24g magnesium

no. of atoms of Mg=( n)× avagdro number

= [(given mass)/ molar mass of Mg] × 6.023× 10^23

=(24/24) × 6.023×10^23

=1×6.023×10^23

= 6.023×10^23_______________eq2

b) 12g carbon

no. of atoms of C=( n)× avagdro number

= [(given mass)/ molar mass of C] × 6.023× 10^23

=(12/12) × 6.023×10^23

=1×6.023×10^23

= 6.023×10^23_______________eq3

c)8g oxygen gas

no. of molecules of O gas=( n)× avagdro number

= [(given mass)/ molecular mass of O gas] × 6.023× 10^23

= 8/16×6.023× 10^23

= 3.011×10^23_____________eq4

Now equation 1 and 4 are equal

therefore,,,,,,,,

answer is option C

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