Siobhan wants to measure the mass of a bag of flour. what should she do?

The most common mistake when people want to measure the mass is they cannot tell the difference between weight and mass.

When you simply put the flour on a normal scale, you're measuring it's weight because it also included the gravitational pull which make the results larger then the original mass.

The measure the mass of the flour she can either :
- Go to and put it on a normal scale in an area with zero gravity
- or she can use some instrument called "balance scale" , in which she can measure the mass from different altitude and compared it

The answer is the first option just took the test

Answer two atoms of oxygen;