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slamgirl [31]
4 years ago
14

Which geologic time did humans exist​

Chemistry
1 answer:
masha68 [24]4 years ago
8 0

<h2><u>PLEASE MARK BRAINLIEST!</u></h2>

It is believed that, 66 million years ago, the first human lived. This is according to fossil. It is thought that, after the Cretaceous–Paleogene extinction [the extinction of dinosaurs and 3/4 of plant and animal life], the first humans appeared.

I hope this helps!

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What would happen to the ecosystem if there were no nitrogen-fixing bacteria
Gre4nikov [31]
Essentially all the available nitrogen for life in the form of nitrates and ammonia would eventually disappear. Nitrogen is needed to make proteins and other chemicals so it is required for all life to exist. It gets recycled so it would take many decades in most places before the available nitrogen ran out. Many crops like beans depend on it. Humans can manufacture it but it would be hard on the ecosystems of the world and eventually probably lead to the extinction of all the ecosystems of the world.


Hope this helps!
4 0
3 years ago
I need help please asap
Margaret [11]

Answer:

Bonding in chemistry is known as chemical bonding which means the interaction or attraction between molecules.

Chemical bonds are of different type such as ionic, covalent, hydrogen, and metallic. Ionic bonds are formed by the transfer of valence electron from one atom to other and there is unequal distribution of electrons between two or more atoms. Ionic bonds forms two oppositely charges ions positively charged (loses electron) or negatively charged (gains electron).

Covalent bond are the strong chemical bonds that form due to equal sharing of electron pairs between atoms. They form a stable element and have stable attraction or repulsive forces.

8 0
3 years ago
Given the following reaction: 2H2(g) + O2(g) à 2H2O(g) answer the following questions:
lora16 [44]

Answer:

Explanation:

2 moles hydrogen reacts with one mole of oxygen to give 2 moles of water.

a ) rate of consumption of hydrogen ( moles per second)  is twice the rate of consumption of oxygen .

b ) rate of formation of water ( moles per second ) is twice the rate of consumption of oxygen

c ) rate of formation of water ( moles per second ) is equal to  the rate of consumption of hydrogen.

6 0
3 years ago
What is the pH of a solution with hydrogen ion concentration of 1 x 10^–6 M?
kakasveta [241]

Answer:

The pH of the solution is 6,00.

Explanation:

The pH indicates the acidity or basicity of a substance. pH values between 0 and less than 7 indicate acidic solutions, 7 neutral and greater than 7 to 14 basic. It is calculated as:

pH = -log (H +)

pH= -log (1x10^-6)

<em>pH= 6, 00</em>

7 0
3 years ago
What is the formula of Potassium oxide??​
Mashutka [201]
<h3>♫ - - - - - - - - - - - - - - - ~Hello There!~ - - - - - - - - - - - - - - - ♫</h3>

➷ The formula for Potassium oxide is K2O

This is because potassium has a 1+ charge and the oxygen has a 2- charge. Two potassium atoms are required to balance the charge.

<h3><u>✽</u></h3>

➶ Hope This Helps You!

➶ Good Luck (:

➶ Have A Great Day ^-^

↬ ʜᴀɴɴᴀʜ ♡

5 0
3 years ago
Read 2 more answers
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