a) By how much does the mass decrease when a hydrogen atom is formed from a prot

Question

a) By how much does the mass decrease when a hydrogen atom is formed from a proton and an electron? Give your answer in atomic mass units.

b) By how much does the mass decrease when a hydrogen atom is formed from a proton and an electron? Give your answer as a percentage of the mass of the hydrogen atom.

c) By how much does the mass decrease when a helium nucleus is formed from two protons and two neutrons? Give your answer in atomic mass units.

d) By how much does the mass decrease when a helium nucleus is formed from two protons and two neutrons? Give your answer as a percentage of the mass of the helium nucleus.

Please show formulas and answers

Explanation / Answer

formula for mass decrease dm =( Zmp+Nmn)-M

Z = proton no , N = neutron no , mp = mass of the proton , mn =mass of neutron

M = mass of the atom

mass decrease when a hydrogen atom is formed from a proton and an electron

= (1.007284 - 1) = 7.284x 10^-3 amu

percentage of mass decrease is 7.284x 10^-3 x 100 = 0.7284

the mass decrease when a helium nucleus is formed from two protons and two neutrons

= 2(1.007284u)+2(1.008664u)-4 u = 0.031896 u = 0.031896 amu

percentage = 0.031896 x 100 = 3.1896

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