Final answer:
The expression that represents the mass of two grains of salt, approximately one microgram or 0.000001g, in scientific notation is 1 x 10-6g.
Step-by-step explanation:
The expression that represents the mass of two grains of salt, approximately one microgram or 0.000001g, in scientific notation is 1 x 10-6g.
Scientific notation is a way to express numbers that are extremely large or small in a more manageable format. In scientific notation, a number is written as a coefficient multiplied by a power of 10. The coefficient must be greater than or equal to 1 and less than 10, and the power of 10 represents how many places the decimal point needs to be moved to get the original number.