Pb has an atomic number of 82. It has an isotope Pb-207. The mass number is 207. How many protons are in Pb 207?
O 82
125
O 207
none of these

Number of protons = 82

Explanation:

Given data:

Atomic number of Pb = 82

Mass number of Pb-207 = 207

Number of protons = ?

Solution:

An atom consist of electron, protons and neutrons. Protons and neutrons are present with in nucleus while the electrons are present out side the nucleus.

All these three subatomic particles construct an atom. A neutral atom have equal number of proton and electron. The sum of neutrons and protons is the mass number of an atom while the number of protons are number of electrons is the atomic number of an atom.

Atomic number of Pb = number of protons or electrons

82 = number of protons or electrons

Mass number = Number of protons + number of neutron

207 = 82 + number of neutron

Number of neutrons = 207 - 82

Number of neutrons = 125

b. accuracy of the data matters alot more than its number of digits, organization or amount of detail. quantitative observation is more accepted than the qualitative observation.