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

dynamic equilibrium is the answer.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.