For fe, its atomic number is 26 and its mass number is 56. how many neutrons does it have? a 26 b 30 c 56 d 82 plato

Answer : The correct option is, (B) 30

Explanation :

Atomic number : It is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Atomic mass : It is defined as the sum of number of protons and number of neutrons.

Atomic mass = Number of protons  + Number of neutrons

or,

Atomic mass = Atomic number  + Number of neutrons

As we are given that,

The element is. Fe

Atomic number = 26

Mass number or atomic mass = 56

Atomic mass = Atomic number  + Number of neutrons

Number of neutrons = Atomic mass - Atomic number

Number of neutrons = 56 - 26

Number of neutrons = 30

Therefore, the number of neutrons are, 30

a. the law of proportion states the combination of 2 atoms in a specific ratio to produce multiple compounds such as the given statement of question ‘1st compound contains 88.8 % cu ’ indicates 88.8 g of cu is present along with 11.2 g oxygen in 100 g of compound whereas the statement ‘2st compound contains 79.9 % cu ’ indicates 79.9 g of cu is present along with 20.1 g oxygen in 100 g of compound

1st compound contains 88.8 g cu

for cu

m = 63 g /mol

atomic % = 88.8 /63 = 1.42

for o

m = 16 g /mol

atomic % = 11.2 /16 = 0.7

b. the emperical formula of 1st compound is

cu1.4o0.7

cu2o