An atom of an element X may be written as `._(4)^(9)X`
What does the figure 9 indicate ?
(b) What does the figure 4 indicate ?
(c) What is the number of protons in atom X ?
(d) What is the number of neutrons in atom X ?
(e) What is the number electron in atom X ?
(f) How many electrons are there in the outermost shell of an atom of element X ?
(g) Write the symbol of ion formed by an atom of element X.

Answer

(a) Mass number (b) Atomic number (c) 4 (d) 5 (e) 4 (f) 2 (g) `X^(2+)`.