CBSE Class 9 Answered
(a)The composition of nuclei of two atomic species X and Y are given below:
X
Y
Protons
17
17
Neutrons
18
20
Find the mass number of X and Y. State the relationship between X and Y.
(b)The K shell is completely filled and L shell of an atom is half filled.Find the number of electrons present in it. State the name of this element.
Asked by Topperlearning User | 14 Jul, 2014, 04:57: PM
Expert Answer
(a) Mass number = No. of protons + No. of neutrons
So, mass number of X = 17 + 18 = 35
Mass number of Y = 17 + 20 = 37
X and Y are isotopes of same element since number of protons is same (same atomic number) in both.
(b) Numbers of electrons = 6 since:
|
K |
L |
|
2 |
4 |
Name of the element = Carbon with atomic number 6.
Answered by | 14 Jul, 2014, 06:57: PM
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