Question

(d) An element X having atomic number 19 reacts with Y having atomic no. 17 to form a compound.[5]

Answer the following questions based upon the above data.

i) Calculate the valency of X and Y

ii) What is the chemical formula formed between X and Y?

iii) Which of the above is a metal and which is a non-metal?

iv) Why do X and Y reacts ?

v) Name the electropositive and electronegative elements?
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Answer 1

Answer:

(i) Compound with atomic no. 19 is K (potassium)

and thus its valency is 1

and compound with atomic no. 17 is Cl (chlorine)

and thus its valency is 1

(ii) chemical formula = x y

1 (crisscross method) 1

this XY is the formula

(iii) Potassium(X) is a metal whereas Chlorine(Y) is a non metal