Question

sodium crystallizes in BCC unit cell what is the approximate number of unit cells in 4.6 gram of sodium

Answer 1

Hi!

Here is the answer to your question.

 

Let the tens digit be x and the ones digit be y.

x + y = 9  … (1)

Original number = 10x + y

Reverse number = 10y + x

Given, Reverse number = Original number + 27

∴10y + x = 10x + y + 27 

⇒ 9y – 9x = 27

⇒ y – x = 3  … (2)

Adding (1) and (2),

⇒ y = 6

When y = 6,

x + 6 = 9  (Using (1))

x = 9 – 6 = 3

∴ Original number = 10x + y = 10 × 3 + 6 = 30 + 6 = 36

 Hope it help....
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Answer 2

Atomic mass of sodium = 23 g

This means, 23 g of sodium contains 6.023 x 1023 atoms



Now, number of atoms in a unit cell of bcc structure = 2

Therefore,

the number of unit cells which contain 1.20x10 23 =1.20x10 23
/2 atoms

   = 6 x 1022 unit cells.