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Kryger [21]
2 years ago
6

About how many times longer than modern humans have hooved mammals lived on earth?

Chemistry
1 answer:
abruzzese [7]2 years ago
8 0

Answer:

I think it should be about maybe the times of the dinosaurs

also I think 23 to 16 billion years

Explanation:

No explanation sorry if im wrong

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Please help me
Wittaler [7]

Answer:

pH = 6.999

The solution is acidic.

Explanation:

HBr is a strong acid, a very strong one.

In water, this acid is totally dissociated.

HBr + H₂O  →  H₃O⁺  +  Br⁻

We can think pH, as - log 7.75×10⁻¹² but this is 11.1

acid pH can't never be higher than 7.

We apply the charge balance:

[H⁺] = [Br⁻] + [OH⁻]

All the protons come from the bromide and the OH⁻ that come from water.

We can also think [OH⁻] = Kw / [H⁺] so:

[H⁺] = [Br⁻] + Kw / [H⁺]

Now, our unknown is [H⁺]

[H⁺] =  7.75×10⁻¹² + 1×10⁻¹⁴ / [H⁺]

[H⁺] = (7.75×10⁻¹² [H⁺] + 1×10⁻¹⁴) /  [H⁺]

This is quadratic equation:  [H⁺]² - 7.75×10⁻¹² [H⁺] - 1×10⁻¹⁴

a = 1 ; b = - 7.75×10⁻¹² ; c = -1×10⁻¹⁴

(-b +- √(b² - 4ac) / (2a)

[H⁺] = 1.000038751×10⁻⁷

- log [H⁺] = pH → 6.999

A very strong acid as HBr, in this case, it is so diluted that its pH is almost neutral.

8 0
3 years ago
A 40.0-mL sample of 0.100 M HNO2 (Ka = 4.6 x 10-4 .) is titrated with 0.200 M KOH. Calculate: a. the pH when no base is added b.
In-s [12.5K]

Answer:

a) 2.173

b) 20ml

c) 3.87

d) 4.35

e) 8.8

f) 12.45

Explanation:

chech the attachment for explanationns

4 0
3 years ago
Resonance in air columns is used in which of these musical Instruments?
AnnZ [28]
Resonance in air columns is used in a variety of musical woodwind instruments. Something like a flute for example uses resonance to make sound. Not sure what instruments you are talking about unless you provide a list.
5 0
3 years ago
Read 2 more answers
How many grams of Sodium will have the same number of atoms as 6 grams of Magnesium?
Ksivusya [100]

Answer:

92gm

Explanation:

Atomic mass of Mg=24g=1 mole of Mg

∴  24g =1 mole of Mg contain 6.022×10^23 atom 

∴  6gm contains 246.022×1023×6

                            =4×6.022×10^23 atoms

Now according to question, there are 6.022×1023 atoms of Na 

23gm of Na contains 6.022×10^23 atoms

∴6.022×4×10^23 atoms of Na weighs 23×6.022×10^23×4/6.022×10^23⇒92gm

3 0
3 years ago
What is the condensed structural formula of the product of the reaction of 2,7-dimethyl-4-octene with hydrogen and a metal catal
gavmur [86]
  The  condensed  structural  formula  of the  product  of the  reaction of 2,7-dimethyl-4-octene  with hydrogen   and metal  catalyst.

 Ch3 CH(CH3) CH2 CH2 CH2 CH2 CH(CH3) CH3

Equation  is  as follows

 CH3 CH(CH3) CH2  C=C CH2 CH(CH3)  CH3  +  H2
→

CH3 CH(CH3)CH2 CH2 CH2 CH2 CH(CH3) CH3

metal catalyst  example is nickel  and the name  of structure formed is 
2,7-  dimethyl octane
6 0
3 years ago
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