Question

An element x on exposure to moist air turrns brown and and a new compound y is formed . The substance X and Y are
X=Fe ,Y=Fe2O3
X=Ag,Y=Ag2S
X=Cu,Y=CuO
X=Al,Y=Al2O3

Answer 1

first option is the right answer as fe i.e, iron gets rusted in moist air and
Fe +O2----Fe2O3.

Answer 2

Answer: The correct answer is $X=Fe,Y=Fe_2O_3$

Explanation:

When iron is exposed to air and moisture, it results in the formation of a reddish brown colored compound known as rust. The chemical formula for this compound is $Fe_2O_3$ and chemical name for this compound is ferric oxide.

The chemical equation for the formation of rust follows:

$4Fe(s)+3O_2(g)\rightarrow 2Fe_2O_3(s)$

By Stoichiometry of the reaction:

4 moles of iron metal reacts with 3 moles of oxygen gas to produce 2 moles of ferric oxide.

Hence, the correct answer is $X=Fe,Y=Fe_2O_3$