She can put chalk in vinegar as the vinegar will disintegrate the chalk chemically demonstrating chemical changes. But for physical changes she can break the chalk into small pieces by smashing it with something or her hand.
There are two conditions necessary for total internal reflection, which is when light hits the boundary between two mediums and reflects back into its original medium:
Light is about to pass from a more optically dense medium (slower) to a less optically dense medium (faster).
The angle of incidence is greater than the defined critical angle for the two mediums, which is given by:
θ = sin⁻¹(
/
)
Where θ = critical angle, = refractive index of faster medium, = refractive index of slower medium.
Choice C gives one of the above necessary conditions.
Answer:
False
Explanation:
Low humidity is typically associated with cold temperatures since cold air holds less water compared to warm air. While it is possible for indoor humidity to be as low as 10%, most people generally find humidity levels of about 40 to 45 percent comfortable.
Answer:
You will be able to tell whether the unknown cell is from an animal or from a plant through the knowledge of difference between plants and animal cells.
Explanation:
A cell can be defined as the simplest bit of living matter which exhibits a variety of shapes and sizes and that can exist independently.
When a slide of an unknown cell is studied under a microscope, different cell structures would be observed which would be used to conclude if the cell on the slide is a plant or animal cell.
The following features are observed in a plant cell:
--> cellulose cell wall is present
--> Chloroplast is present
--> A large central vacuole is present
--> Centriole is absent
The following features are observed in animal cell:
--> Cellulose cell wall is absent
--> Chloroplast is absent
--> Small vacuoles is present
--> Centriole is present
The difference between a plant and an animal cell can be seen from the features above and a clear knowledge of this will help the student tell whether the unknown cell is from an animal or from a plant.
The electrons in the positive object are attracted to the negatively charged object. Some of the electrons move from the positive object to the negative object.
an example of this is lightning because the positive electrons on/in the earth are attracted to the negative electrons in the clouds and sky so the positive move to the negative charge.
