Q5 of 40 Page 130

Calculate the number of neutrons, protons and electrons (i) atomic number 3 and mass number 7 (ii) atomic number 92 and mass number238.

i) Given,


Atomic Number = 3


Mass Number = 7


Therefore,


No. of electrons = atomic number = no. of protons = 3


And,


Mass Number = no. of protons+ no. of neutrons = 7


Thus, no. of neutrons = 4


ii) Given,


Atomic Number = 92


Mass Number = 238


Therefore,


No. of electrons = atomic number = no. of protons = 92


And,


Mass Number = no. of protons+ no. of neutrons = 238


Thus, no. of neutrons = 238-92 = 146


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