Answer:
8%
Explanation:
Given that,
Mass of solute = 8 g
Mass of soultion, (mass of alloy) = 100 g
We need to find the percent by mass of 8.0g copper is added to enough zinc to produce 100g an alloy. It can be calculated by the formula as follows :

So, the percent by mass is 8%.
Answer:
The amount of light they receive.
Explanation:
In an experiment, the independent variable is the part of the experiment that the experimenter changes. In this experiment, the only thing that's different for each of the plants is the amount of light they receive. Everything else is the same - the same amount of soil, same amount of water, same pots, and so on.
Answer:
d. transcription factors
Explanation:
Transcription factors are the proteins present in cells that are involved in the regulation of gene expression. The transcription factors may increase or decrease the expression of a gene. Therefore, a transcription factor may serve as an activator or repressor for a gene. These proteins bind to a regulatory sequence present near or within a gene, interact with RNA polymerase or other transcription factors and thereby, affect the transcription initiation.
Since binding of dioxin to certain proteins alter the pattern of gene expression in the cells, these proteins are the transcription factors. For instance, dioxin may bind to a transcription factor and up-regulate the expression of genes which in turn regulate the cell division.
<span>A gradual increase in atmospheric carbon dioxide would warm earths atmosphere becuse carbon dioxide is <em>a greenhouse gas</em></span>