Answer:
a. 
Step-by-step explanation:

Find the change
the change is 63-21=42
42 degrees in 12 hours
we want to find xdegrees/1hour
42/12=3.5 degrees per hour
To find the cost per pound of rice, we can divide.
10 / 24 ≈ $0.42
A pound of rice approximately costs $0.42
Best of Luck!
The mass of sodium chloride required for 1. 8 × 10^3 people is 3. 6 × 10^5 grams. Option A is the correct answer.
<h3>
How do you calculate the mass of sodium chloride required?</h3>
Given that weigh of the person is 50 KG. The mass of the sodium chloride in one person is given below.

The mass of sodium chloride is calculated as given below.


Hence we can conclude that the mass of sodium chloride required for 1. 8 × 10^3 people is 3. 6 × 10^5 grams. Option A is the correct answer.
To know more about the mass, follow the link given below.
brainly.com/question/15959704.