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Mariulka [41]
3 years ago
8

When did homo spiens leave africa

Chemistry
1 answer:
german3 years ago
7 0

homo sapiens leave africa at approximately 200,000 years ago.

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Water has a specific heat of 4.186 J/g*C. How much energy would be required to raise the temperature of 10 g of water by 10 C?
Sladkaya [172]

Energy(heat) required to raise the temperature of water : 418.6 J

<h3>Further explanation  </h3>

Heat can be calculated using the formula:  

Q = mc∆T  

Q = heat, J  

m = mass, g  

c = specific heat, joules / g ° C  

∆T = temperature difference, ° C / K  

Specific heat of water = 4.186 J/g*C.

∆T(raise the temperature) : 10° C  

mass = 10 g

Heat required :

\tt Q=m.c.\Delta T\\\\Q=10\times 4.186\times 10\\\\Q=418.6~J

8 0
3 years ago
The moving of molecules from areas of high concentration to that of low concentration to gain energy is best described as
seropon [69]

The moving of molecules from areas of high concentration to that of low concentration to gain energy is best described as passive transport

<h3>What is passive transport?</h3>

Passive transport is a type of membrane transport in which chemicals are moved across cell membranes without using energy. Unlike active transport, which uses cellular energy, passive transport uses the second law of thermodynamics to cause the movement of substances across cell membranes.

<h3>Why is passive transport important?</h3>

Passive transport processes are critical to homeostasis. They maintain proper conditions inside the cell and the organism as a whole by letting chemicals to pass into and out of the cell.

To know more about Passive transport  visit:

brainly.com/question/13542102

#SPJ4

7 0
2 years ago
What is the mole fraction of acetic acid in a solution containing 2 moles of vinegar and 3 moles of water? A. 2 B. 3 C. 0.4 D. 0
9966 [12]

Answer:

C. 0.4.

Explanation:

<em>∵ mole fraction of acetic acid (X acetic acid) = (no. of moles acetic acid)/(total no. of moles) = (no. of moles acetic acid)/(no. of moles of acetic acid + no. of moles of water).</em>

<em></em>

- no. of moles of acetic acid = 2, no. of moles of water = 3.

- Total no. of moles = no. of moles of acetic acid + no. of moles of water = 2 + 3 = 5.

<em>∴ mole fraction of acetic acid (X acetic acid) = (no. of moles acetic acid)/(total no. of moles) =</em> (2)/(5)<em> = 0.4.</em>

3 0
3 years ago
Read 2 more answers
Arrange the compounds by their reactivity toward electrophilic aromatic substitution.
swat32

Answer:

The order of reactivity towards electrophilic susbtitution is shown below:

a. anisole > ethylbenzene>benzene>chlorobenzene>nitrobenzene

b. p-cresol>p-xylene>toluene>benzene

c.Phenol>propylbenzene>benzene>benzoic acid

d.p-chloromethylbenzene>p-methylnitrobenzene> 2-chloro-1-methyl-4-nitrobenzene> 1-methyl-2,4-dinitrobenzene

Explanation:

Electron donating groups favor the electrophilic substitution reactions at ortho and para positions of the benzene ring.

For example: -OH, -OCH3, -NH2, Alkyl groups favor electrophilic aromatic substitution in benzene.

The -I (negative inductive effect) groups, electron-withdrawing groups deactivate the benzene ring towards electrophilic aromatic substitution.

Examples: -NO2, -SO3H, halide groups, Carboxylic acid groups, carbonyl gropus.

4 0
3 years ago
What is the percent of O in<br> CO2?
katen-ka-za [31]

Answer:

72.7% of oxygen

Explanation:

8 0
3 years ago
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