A 54-gram sample of an unknown material has a volume equal to 20 20 cm 3. what is the identity of the substance?
a.lead
b.steel***
c.aluminum
d.mercury
An ice cube, a glass of cold water, and a swimming pool are each exposed to the same amount of sunlight on a hot day. after five minutes, the ice cube is melted and the cold drink is two degrees warmer, but the tempature of the swimming pool remains unchanged. what is the best explanation for these observations.
A. The ice cube has a higher capacity than the glass of water
and pool***
B.The ice cube has a lower capacity than the glass of water and pool.
C. The ice cube and the glass of water have higher heat capacities than the swimming pool
d.The ice cube and the glass of water have lower heat capacities than the swimming pool
A banana turning brown when exposed to the air is an example of
A.a heterogeneous mixture.
B.vaporization
C.a chemical change***
D.an amorphous solid
anybody
To determine the identity of the substance in the first question (54-gram sample with volume equal to 20 cm^3), we can calculate the density of the material. Density is defined as mass divided by volume, so we can calculate the density by dividing the mass (54 grams) by the volume (20 cm^3).
Density = Mass / Volume
Density = 54 g / 20 cm^3
By dividing these numbers, we find that the density of the substance is 2.7 g/cm^3.
To identify the substance, we can compare this density to the known densities of different materials.
Out of the options given, Steel has a density of about 7.8 g/cm^3, which is significantly higher than the calculated density. Therefore, Steel is not the correct answer.
Lead has a density of about 11.3 g/cm^3, also significantly higher than the calculated density. Therefore, Lead is not the correct answer.
Aluminum has a density of about 2.7 g/cm^3, which matches the calculated density. Therefore, Aluminum could be the identity of the substance.
Mercury has a density of about 13.6 g/cm^3, significantly higher than the calculated density. Therefore, Mercury is not the correct answer.
Based on the calculated density matching the density of Aluminum, the correct answer would be c. Aluminum.
For the second question, the best explanation for the observations is:
C. The ice cube and the glass of water have higher heat capacities than the swimming pool.
Heat capacity is the amount of heat energy required to raise the temperature of an object by a certain amount. The ice cube and the glass of water have lower heat capacities compared to the swimming pool. As a result, the ice cube is able to melt, and the glass of water is able to increase in temperature more quickly compared to the swimming pool, which requires more heat energy to change its temperature.
Lastly, a banana turning brown when exposed to the air is an example of a chemical change. Chemical changes involve the formation or breaking of chemical bonds, resulting in the formation of new substances. The browning of a banana occurs due to a chemical reaction between enzymes in the banana and oxygen in the air, leading to a change in the composition and structure of the banana, resulting in the brown color. Therefore, the correct answer is C. a chemical change.