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Q. Element A has 2 electron in its M shell. Element B has atomic number 7. 
(a) Write equations to show how A and B form ions. 
(b) If B is a diatomic gas, write the equation for the direct combination of A and B to form a compound. 
(c) If the compound formed between A and B is melted and an electric current is passed through the molten compound, the element A will be obtained at the ....... and B at the ......... of the electrolytic.

Dear Student,
Electronic configuration of A = 2,8,8,2 
So A atomic number is 20 which is element Calcium. 
B atomic number is 7 which is element Nitrogen.
Electronic configuration of B is 2,5.
(a) A - 2e- -----> A2+ 
      B + 3e- -----> B3-
(b)3A + B2 ---> A3B2 
(c) A will be obtained at cathode because A has tendency to get oxidised and B will be obtained at anode because B has tendency to get reduced. 
Regards

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A-Mg and B-N(nitrogen)
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Hope this helps.....

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Please find this answer

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(a) A - 2e- -------> A2+
B + 3e- -------> B3-
(b) A + B2 -------> A3B2
(c) A will go to cathode but B will go to anode
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Hope its clear
Thank you

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Hi there,

Here's the solution:-

Possible Electronic configuration[ EC] of A = 2,8,8,2
Thus A's atomic no. is 20 ( Calcium)

B's atomic no. = 7
Its EC is 2,5

(a) A - 2e? ---> A?+
B + 3e? ---> B??

(b)3A + B2 ---> A3B2

(c) A will be obtained at cathode and B will be obtained at anode.

P.S. :- If you are an ICSE student then remember that never use their actual names, even if you identify the elements. Use the letters given in the question to solve it.

Hope you got it (^_^)
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