Answer:
The dependent variable is the number of clams developing from fertilized eggs.
The independent variable is the water temperature
The optimum temperature for clam development is 30 degrees centigrade.
Explanation:
The graph of the number of clams developing from fertilized eggs and water temperature is attached to this answer.
The independent variable is being manipulated in an experiment. As it changes, it produces a corresponding change in the dependent variable.
Here, the water temperature is the independent variable. As it changes, the number of clams developing from fertilized eggs (dependent variable) also changes alongside.
The optimum temperature is the temperature at which the greatest number of clams developing from fertilized eggs is produced. We can see from the graph that this temperature is 30 degrees centigrade.
We know this because of the discovery of fossils and bones. We can find out roughly when they existed because of carbon dating.
Answer:
A. body muscles
The pressure needed to pump blood back to the heart is produced by the <u>body </u><u>muscles </u><u>.</u>
Answer:
A. a new substance is being produced.
Explanation:
The bubbles most likely indicates that a new substance is being produced by this reaction. In essence, we describe this sort of change as chemical change.
In a chemical change, new substances are usually produced. They are accompanied by the evolution or absorption of energy.
The reaction of Zinc with a strong acid to produce bubbles on the surface of the metal indicates a chemical change and the formation of a new kind of substance.
Take for example, let zinc reacts with hydrocholoric acid, HCl;
Zn + 2HCl → ZnCl₂ + H₂
Since Zn is higher than Hydrogen in the activity series, it will displace it from HCl and liberate hydrogen gas as a product. This will cause the bubbles observed in the reaction.
This is a chemical change and new products have been formed.
B and D are wrong because they are both physical changes.
C is wrong because no information about such is provided by the problem statement.
So, when a piece of zinc metal combines with a strong acid, a new kind of substance is produced.
