Index fossils<span> can be </span>used<span> to help determine the relative age of </span>rock<span> layers. </span>Index fossils<span> are from species that only existed for a short time. </span>Index fossils<span> are found in</span>rock<span> layers. Trilobites and Graptolites are </span><span>index fossils.</span>
Answer:
- First: element.
- Second: Compound.
- Third: element.
- Fourth: Compound.
Explanation:
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In this case, since elements are composed the same atom and compounds are composed by two different atoms, we can see that:
- First: it is an element as each sphere seems to be the same.
- Second: It is a compound as two different type of spheres are shown, white and black, considering each sphere is a different element.
- Third: it is an element because the spheres are equal, in fact, it is a diatomic element as two atoms are joined per molecule.
- Fourth: It is a compound as well since each molecule has two colored spheres and one white sphere, meaning that it has two different atoms per molecule.
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The state of matter that has no definite shape but has a fixed volume is B. Liquid.
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Below are the choices:
A.) an unpaired electron,
<span>B.) a nonbonding electron pair, </span>
<span>C.) a bonding electron pair, </span>
<span>D.) a high value of electronegativity
</span>
The correct answer is B.) a nonbonding electron pair,