Polycarbonate plastic has a density of 1.2 g/cm3. A photo frame is constructed from
two 5.2 mm sheets of polycarbonate. Each
sheet measures 22 cm by 20 cm.
What is the mass of the photo frame?

The mass of the photo frame : = 549.12 g

Given

a photo frame

two 5.2 mm sheets = 0.52 cm

22 cm by 20 cm dimension

Required

the mass

Solution

The volume of one sheet = l x w x h

= 22 cm x 20 cm x 0.52 cm

= 228.8 cm³

Mass of one sheet :

= density x volume

= 1.2 g/cm³ x 228.8 cm³

= 274.56 g

So for two sheets of polycarbonate :

= 2 x  274.56 g

= 549.12 g

answer is: c. the experiment shows that the red substance experienced a chemical change.

this is chemical change (chemical reaction), because two new substances are formed (metalig liquid and gas), the atoms are rearranged and the reaction is followed by an energy change.

this is example of chemical decomposition.

chemical decomposition (analysis) is the separation of a single chemical compound into its two or more elemental parts or to simpler compounds.  

chemical decomposition is opposite of chemical synthesis.

i just calculated it all out, and not including weekends, and all the different days off. as of this school year (2018-2019) students are spending 2198 hours in school this year