Which missing item would complete this alpha decay reaction?

#""_(98)^(251) "Cf" -> ""_(96)^(247) "Cm" + "___"#

#A.# #""_(-1)^(0) "e"#

#B.# #""_(97)^(247) "Bk"#

#C.# #""_(2)^(4) "He"#

#D.# #""_(92)^(238) "U"#

#E.# #""_(0)^(0) gamma#

1 Answer

Answer:

#"Option" C-> ""_2^4He#

Explanation:

#"The decay would have helium left after the reaction."#

#""_98^251 Cf → ""_96^247Cm +""_2^4He #

#"We know the atomic masses of the elements but we do not know"#
#"know the number of protons of the substances ."#
#" But for this reaction number of neutrons are also required "#

First determine the number of neutrons in Cf

#"no. of neutrons = atomic weight - no. of protons"#

#"251 - 98 = 153 neutrons"#

Then determine the number of neutrons in Cf

#"no. of neutrons = atomic weight - no. of protons"#

#"247 - 96 = 151 neutrons"#

This means there are more 2 protons and neutrons

#"Decay in neutrons"#

#98 → 96 + 2#

#"Decay in protons"#

#153 → 151 + 2 # helium atom as the electrons are number of electrons = no. of protons

Energy can be neither created nor destroyed .

Protons and neutrons are energy in scientific words

As energy cannot be destroyed so 251 → 247 cannot happen and there should be something more .

This is an alpha decay equation so this means there are more 2 electrons and neutrons which mean that the element is Helium without its electrons.An
α
particle is 2 protons and 2 neutrons bound together like they are within the nucleus of a Helium atom; it is so like a Helium nucleus that it is often written as #4/2He2+#