Here, It is said that a burning ribbon of a metal was taken in a jar containing gas and it formed white and black powder.

We know, When burning magnesium is inserted into a jar containing carbon dioxide, it burns continuously and forms magnesium oxide(white) and carbon(black)
So, the white substance is Magnesium oxide (\(\rm MgO\)).

1.Ans:

When the white powder (magnesium oxide, MgO) is dissolved in water, it forms magnesium hydroxide. The balanced chemical equation for this reaction is:

\(\rm MgO\) + \(\rm H_{2}O\) → \(\rm Mg(OH)_{2}\)

2.Ans:

Magnesium hydroxide acts as an antacid. When it dissolves in the stomach, it reacts with excess hydrochloric acid (HCl) to form magnesium chloride (\(\rm MgCl_{2}\)) and water, which helps neutralize the acidity. This reaction reduces the overall acidity in the stomach, relieving symptoms of hyperacidity.

The neutralization reaction can be represented as follows:

\(\rm Mg(OH)_{2}\) +\(\rm 2HCl\) → \(\rm MgCl_{2}\) + \(\rm 2H_{2}O\)