How many moles are in 4.81x10^24 atoms of boron(B) ? Show all of your work. Include units. round your answer to the correct number of significant figures.

7.99 moles of boron

Explanation:

Given data:

Number of moles of B = ?

Number of atoms of B = 4.81 × 10²⁴ atom

Solution:

Avogadro number:

The given problem will solve by using Avogadro number.

It is the number of atoms , ions and molecules in one gram atom of element, one gram molecules of compound and one gram ions of a substance.  The number 6.022 × 10²³ is called Avogadro number.

1 mole = 6.022 × 10²³ atoms

4.81 × 10²⁴ atom × 1 mol / 6.022 × 10²³ atoms

0.799 × 10¹ mol

7.99 moles

when the volume of gas is   changed from   717.73 ml   to 852 ml   the temperature will   change   from 315   c to 452   c

    calculation

this is calculated using the charles law formula

that is,   v1/t1 = v2/t2

          v1=?

        t1 = 315 c   into   kelvin = 315 +273 = 588 k

        v2 = 852   ml

        t2 = 425c + 273 =698 k

make v1   the subject of the formula ( by   multiplying both side by t1)

  v1=( v2 xt1) / t2

v1= (852 ml   x 588 k)/ 698 k= 717.73 ml