All organisms need oxygen to survive
Answer:
testable questions are answer through observation or an experiment that provides evidence that the questions connects to the scientific concepts rather the opinion feelings
therefore the question can be tested through observation or experiment
<span>A lahar is a type of mudflow that occurs after a volcanic eruption. It is a sort of mudflow or trash stream made out of a slurry of pyroclastic material, rough flotsam and jetsam, and water. The material streams down from a fountain of liquid magma, normally along a waterway valley. Lahar is the most deadly by-products of the eruption because of the speed they can travel. </span>
A compound is a pure substance formed by the chemical combination of two or more different elements.
A compound may be splitted into simpler substances by chemical reactions, and has different properties to those of the elements that form it.
The composition of a compound is fixed: every piece of a compound has the same kind of atoms, bonded in the same way and proportion.
Some examples of compounds are H₂O, NaCl, H₂O₂, CH₃COOH. As you see, they have a chemical formula which states the kind and number of the atoms that form them.
They are different to mixtures, which are formed by two or more compounds, in a variable proportion, and can be separated by physical media. Some examples of mixtures are the solutions (e.g. NaCl dissolved in H₂O), and some solid mixtures (e.g. a mixture of marbles and sand).
