Question

1. which of the following is not a pure substance?

a. helium
b. carbon dioxide
c. seawater
d. glucose

1. peter places six balls of modeling clay on one side of a balance. he places a pl

it takes 41 plastic cubes to balance the modeling clay. he then removes the clay,
shapes it into a dinosaur, and puts it back on the balance. how many cubes will he m
likely need to put into the cup to balance the dinosaur?
a. 35
b. 38
c. 41
d. 47

Explanation:

Step1: Define pure substances

Pure substances have a fixed - composition. Elements and compounds are pure substances.

Step2: Analyze each option for question 22

Helium is an element, carbon dioxide is a compound, and glucose is a compound. Seawater is a mixture of water, salts, and other substances. So seawater is not a pure substance.

Step3: Apply the law of conservation of mass for question 23

The mass of the clay does not change when its shape is changed. Since 41 plastic cubes balance the clay in ball - form, the same 41 plastic cubes will balance the clay in dinosaur - form.

Answer:

1. c. Seawater
2. c. 41