Identify the exact number(s), if any, in each of the following pairs of numbers:a. 5 pizzas and 50.0 g of cheese

Verified step by step guidance

1. Identify the type of each number: 5 pizzas is a count of items, while 50.0 g of cheese is a measurement.
2. Determine if the numbers are exact or measured: Exact numbers are those that are counted or defined, while measured numbers are obtained using a measuring tool and have some degree of uncertainty.
3. Recognize that 5 pizzas is an exact number because it is a count of whole items, and counting is precise.
4. Understand that 50.0 g of cheese is a measured number because it involves a measurement with a scale, which introduces uncertainty.
5. Conclude that in the pair, 5 pizzas is the exact number, while 50.0 g of cheese is a measured number.

Key Concepts

Exact Numbers

Exact numbers are values that are counted or defined and have no uncertainty associated with them. For example, if you have 5 pizzas, this number is exact because it represents a count of whole items. Exact numbers do not affect the precision of calculations in the same way that measured numbers do.

Measured Numbers

Measured numbers are values obtained from measurements and include some degree of uncertainty. For instance, 50.0 g of cheese is a measured number, as it is derived from a scale and reflects a specific quantity with a defined precision. The number of significant figures in a measured number indicates the level of certainty in the measurement.

Significant Figures

Significant figures are the digits in a number that contribute to its precision. This includes all non-zero digits, any zeros between significant digits, and trailing zeros in the decimal portion. Understanding significant figures is crucial for accurately reporting measurements and performing calculations in chemistry, as they reflect the reliability of the data.