What are the 3 main weapons of a predator?

Ascientist is conducting an investigation that involves water, silver, carbon dioxide, and oxygen gas which group of statements best describes all of the materials he is using in the investigation?

Which soil would most likely be found in the arctic? andisols gelisols histosols spodosols

Sarah performs an experiment to determine the effect of nitrogen on plants. she studies the effect of nitrogen on the growth of the root hair, height of the plants, and nodule formation. which factor is an independent variable?