Q. 2.21 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify each of the following as measured or exact and give the number of significant figures (SFs) in each measured number: 

a. The mass of a neonate is $1.607$ kg.

b. The Daily Value (DV) for iodine for an infant is $130$ mcg.

c. There are $4.02\times {10}^6$ red blood cells in a blood sample.

d. In November, $23$ babies were born in a hospital.

Step-by-Step Solution

Answer

(a) Mass of a neonate is measured.

(b)The Daily Value of iodine for an infant is measured.

(c) Red blood cells in a blood sample are measured

(d) No. of babies born in a hospital is an exact

Part a: Step 1: Given Information

We have been given that the mass of a neonate is $1.607$ kg.

Part a: Step 2: Explanation

Measured numbers are the results of measuring a quantity such as our height or distance. Due to measurement techniques, their values aren't exact.

An exact number can be calculated with absolute accuracy. They can't be simplified or reduced.

Here, it is a measured number and there are four significant digits.

Part b: Step 1: Given Information

We have been given that the Daily Value (DV) for iodine for an infant is $130$ mcg. 

Part b: Step 2: Explanation

Measured numbers are the results of measuring a quantity such as our height or distance. Due to measurement techniques, their values aren't exact.

An exact number can be calculated with absolute accuracy. They can't be simplified or reduced. 

Here, it is a measured number and there are two significant digits.

Part c: Step 1: Given Information

We have been given that there are $4.02\times {10}^6$ red blood cells in a blood sample.

Part c: Step 2: Explanation

Measured numbers are the results of measuring a quantity such as our height or distance. Due to measurement techniques, their values aren't exact.

An exact number can be calculated with absolute accuracy. They can't be simplified or reduced. 

Here, it is a measured number and there are three significant digits.

Part d: Step 1: Given Information

We have been given that in November, $23$ babies were born in a hospital.

Part d: Step 2: Explanation

Measured numbers are the results of measuring a quantity such as our height or distance. Due to measurement techniques, their values aren't exact.

An exact number can be calculated with absolute accuracy. They can't be simplified or reduced. 

Here, it is an exact number.