Answer:
Which statement best describes properties of elements?
A. All elements have a similar structure and hardness.
A. All elements have a similar structure and hardness.
B. All elements have mass and occupy space.
B. All elements have mass and occupy space.
C. All elements are either metals or gases.
C. All elements are either metals or gases.
D. All elements are solid and magnetic.
D. All elements are solid and magnetic.
Explanation:
D) selecting random sample allows for a more representative sample in a survey.
Answer:
Desertification
Explanation:
Drought and leaching leave some parts of Africa without much water, which leads to some portions of the area to turn into a desert, which can prove disastrous for the plants and animals that now find themselves in a completely different habitat.
The variable is the group that was given caffine, because thats what the doctors manipulated. They possibly altered the natural memory of the participants by giving them caffine. A more specific variable could be how much caffine each participant is given and what time are they given it.
