Calculate the mass, in grams, of a single tungsten atom (mw = 183.84 amu ).

The formula for number of moles is :

    -(1)

The atomic mass of tungsten =   (given)

Number of atoms of tungsten = 1

Since, 1 mol =

So, number of moles of tungsten =

Rearranging the formula (1) as:

Substituting the values:

Hence, the mass of a single tungsten atom (mw = 183.84 amu ) is .

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