What is the mass of oxygen in 25.0 grams of potassium permanganate , KMnO4?

10.76 grams

Explanation:

Given that the amount of is 25.0 grams.

Mass of 1 mole of = 158 grams

The number of atoms in 1 mole of is 4.

Mass of oxygen in 1 mole of = 16\times 4 = 68 grams.

Here, 158 grams of has 68 grams of oxygen

So, the amount of oxygen in 1 gram of = 68/158 grams

Therefore,  the amount of oxygen in 1 gram of = grams

=10.76 grams

Hence, 25 grams of has 10.76 grams of oxygen.

answer: c. the experiment shows that the red substance experienced a chemical change.

explanation: chemical change is the change in which chemical composition of the substance changes. physical change is the change in which there is no change in chemical composition.

chemical changes are accompanied by following changes:

a) precipitate formation

b) energy is released or absorbed

c) formation of bubbles

d) change in color

as it is given that the red color has disappeared and there is production of gas, it means the red substance has undergone a chemical change.

e