A large atom decays and emits a particle. After the reaction is complete, the atom’s mass has changed substantially. What kind of particle has most likely been emitted?
alpha particle
beta particle
positron
photon

alpha particle

Explanation:

Alpha decay occurs when a nucleus is unstable because it has too many protons. The nucleus emits an alpha particle and energy. An alpha particle consists of two protons and two neutrons, which is actually a helium nucleus. Losing the protons and neutrons makes the nucleus more stable.

Hence, alpha emission means that the nucleus looses four mass units. Loosing four mass units leads to a substantial change in the mass of the nucleus. Hence the daughter nucleus is four mass units less than than the parent.

c is having 4 valence electrons and is bonded to three hydrogens and one sulphur atom, therefore, the number of bond pair is equal to four. as all the valence electrons are used in forming the bonds so, there is no lone pair left on carbon.

s is having 6 valence electrons and is bonded to one other sulfur atom and one carbon atom, therefore, the number of bond pair is equal to 2. as only two valence electrons are used in forming the bonds so, four electrons are left. therefore, two lone pairs are present on s.

nuclear fission produces elements that are heavier than helium.

the elements that are used in nuclear fission and their products are much heavier than helium.