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mr_godi [17]
3 years ago
10

Humans have used rocks in the creation of tools and building materials true or flase

Chemistry
2 answers:
olga55 [171]3 years ago
8 0

Answer:

true

Explanation:

Anuta_ua [19.1K]3 years ago
4 0
True, if you would like an example look at Indian arrow heads or early architecture all use rocks.
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Why is oxygen spelt o2
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Answer:

it's a diatomic molecule–which is why it is O₂.

Explanation:

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You are given stocks of 4 M NaCl, 40% Glucose, and 1M Tris-HCl (pH 8.5). You need to make 400 ml of a buffer containing 0.5 M Na
OLga [1]

Answer:

50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.

Explanation:

To make 400mL containing 0.5M NaCl you need to add:

4M / 0.5M = 8 (dilution 1/8). 400mL / 8 = <em>50 mL of 4M NaCl.</em>

Glucose 8% you need to add:

40% / 8% = 5 (dilution 1/5). 400mL / 5 = <em>80 mL of 40% glucose </em>

Buffer 50mM you need to add:

1000mM / 50mM = 20 (dilution 1/20). 400mL / 20 = <em>20mL of 1M Tris-HCl (pH 8.5)</em>

<em></em>

The resting volume: 400mL - 50mL of 4M NaCl - 80mL of 40% glucose - 20mL of 1M Tris-HCl (pH 8.5) = 250 mL must be completed with water.

Thus, to make the solution you need: <em>50mL of 4M NaCl, 80mL of 40% glucose, 20mL of 1M Tris-HCl (pH 8.5) and 250mL of water.</em>

<em></em>

I hope it helps!

8 0
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