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Looking at the information given in the description, the experiment is testing for the effects of the different salts on the growth of the plants.
This means that the type of salt is the independent variable, or the variable being manipulated and tested.
To ensure fair results, some parts of the experiment would need to be kept the same, which is the control. The only answer choice that makes sense in this instance is A. water.
Answer:
Henry Moseley
Explanation:
Dmitry Mendeleef and Lothar Meyer proposed a periodic table based on the atomic mass.
They stated a periodic law expressed as "chemical properties of elements are a periodic function of their atomic weights".
But, Henry Moseley in 1900s re-stated periodic law by changing the basis of the law from atomic weight to atomic number.
The present periodic law is stated as "the properties of elements are a periodic function of their atomic number".
Answer: A dilation with rule: 
Explanation:
A dilation is a non-rigid transformation that creates an image that is the same shape as the original but has a different size.
It uses a scale factor k such that

(x,y)= coordinates of original figure
(kx,ky) = corresponding coordinate in the image.
To transform: A (3,-4) onto point A' (1.5,-2).
Using scale factor k=
, we have

Required rule: 