Calculate the number of atoms in a 1.26×103 g sample of silicon.

2.71 x10^25 atoms Si

Explanation: Solution:

1.26x10²³ g Si x 1 mole Si / 28 g Si x 6.022x10²³ atoms Si / 1 mole Si

= 2.71 x10^ 25 atoms Si

the correct option is c.

isotopes refers to different forms of the same element with the same atomic number but different mass number as a result of difference in their neutron numbers. isotopes have different relative atomic mass but share the same chemical properties.