2. What evidence is there that mass extinction events occurred?

1 answer:

5 0

Answer: Although the best-known cause of a mass extinction is the asteroid impact that killed off the non-avian dinosaurs, in fact, volcanic activity seems to have wreaked much more havoc on Earth's biota. Volcanic activity is implicated in at least four mass extinctions, while an asteroid is a suspect in just one. Examples, of mass extinctions are Permian extinction of marine species, and Cretaceous extinction of various species, including dinosaurs.

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Myriah wants to use dimensional analysis to find out how many centimeters (cm) are in 1.4 meters (m).

WINSTONCH [101]

1400 centimeters in 1.4 millimeters

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3 years ago

What is an example of kinetic energy? Question 7 options: A frisbee flying through the air A car in the garage A box sitting on

Amiraneli [1.4K]

Kinetic energy is energy that comes from motion. Anything that is currently in motion has kinetic energy.

Let’s look at each example to determine if they have kinetic energy.

First off, a car in the garage: let’s ask ourselves- Is the car in motion?
No, it is sitting in the garage. It is not moving; therefore it doesn’t have any kinetic energy.

Next, a box sitting on a shelf: let’s ask ourselves the same question- Is the box in motion?
No, it is sitting on the shelf. Again, it is not moving. It doesn’t have any kinetic energy.

Our third item is a ball lodged in a tree: again, we will ask ourselves the same question- Is the object moving?
No, it isn’t moving. Again, since it is not moving, it will not have kinetic energy.

Our last item is a frisbee flying through the air: asking ourselves the same question- Is it moving?
Yes, the object is moving. Yes, it has kinetic energy.

The frisbee flying through the air has kinetic energy.

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3 years ago

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In which reaction does the oxidation number of hydrogen change? In which reaction does the oxidation number of hydrogen change?

dedylja [7]

Answer: The correct answer is $2Na(s)+2H_2O(l)\rightarrow 2NaOH(aq.)+H_2(g)$

Explanation:

Oxidation number is defined as the number which is given to an atom when it looses or gains electron. When an atom looses electron, it attains a positive oxidation state. When an atom gains electron, it attains a negative oxidation state.

Oxidation state of the atoms in their elemental state is considered as 0. Hydrogen is present as gaseous state.

For the given chemical reactions:

Reaction 1: $2HClO_4(aq.)+CaCO_3(s)\rightarrow Ca(ClO_4)_2(aq.)+H_2O(l)+CO_2 (g)$