One of the alkali metals reacts with oxygen to form a solid white substance. when this substance is dissolved in water, the solution gives a positive test for hydrogen peroxide, h2o2. when the solution is tested in a burner flame, a lilac-purple flame is produced. what is the likely identity of the metal?

Potassium (K)

Explanation:

First, you need to know the possible alkali metals, which are:

Sodium (Na), Litium (Li), Potassium (K) and Cesium (Cs), rubidium (Rb).

Now, the reaction that is taking place is the following:

M + O2 > M2On

Where n should be the oxidation state of the metal. In this case, most of the alkalin metals have an oxidation state of +1, so, this number should be 1. However some elements can produce the peroxyde, like litium, sodium and potassium.

The following reaction would be:

M2O + H2O > MOH

Now, the hint here is that the solution is tested with a flame. This, would be, the final hint to know which element this is.

In the case of sodium, litium and potassium, the reactions being held are as following:

Li + O2 > Li2O2         Li2O2 + 2H2O > 2LiOH + H2O2

Na + O2 > Na2O2         Na2O2 + 2H2O > 2NaOH + H2O2

K + O2 > K2O2         K2O2 + 2H2O > 2KOH + H2O2

Now, all of these elements throw a different color in the flame. Litium is a red or crimson. Sodium is usually yellow, and finally the potassium is always purple.

Therefore the identity of this metal would have to be potassium.

chemical digestion occurs in the stomach were hcl and pepsin forms chyme, the mouth in which salivary amylase breaks down starch to form bolus, and the small intestine specifically the duodenum.