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Sever21 [200]
3 years ago
15

when a number in scientific notation contains a significant zero, is that zero also significant in the expanded notation? give t

wo examples to support your answer. PLEASE HELP I NEED ANSWERS ASAP
Chemistry
1 answer:
AlexFokin [52]3 years ago
4 0
I believe you are referring zero as the exponent. <span>Any number (except 0) with exponent 0 is defined to mean 1.
</span>

For one thing, there is a rule: 

<span> a^m/ a^m = a^m-m = a^0

</span>But (when a is not equal to <span>0),
</span>
a^m/ a^m = 1

Therefore, we must define a^0 as 1.

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kifflom [539]

Answer:

its solid

Explanation:

hope it helps u

3 0
3 years ago
Suppose a group of volunteers is planning to build a park near a local lake. The lake is known to contain low levels of arsenic
Kisachek [45]

Answer:

A) 10.75 is the concentration of arsenic in the sample in parts per billion .

B) 7,633.66 kg the total mass of arsenic in the lake that the company have to remove.

C) It will take 1.37 years to remove all of the arsenic from the lake.

Explanation:

A) Mass of arsenic in lake water sample = 164.5 ng

The ppb is the amount of solute (in micrograms) present in kilogram of a solvent. It is also known as parts-per million.

To calculate the ppm of oxygen in sea water, we use the equation:

\text{ppb}=\frac{\text{Mass of solute}}{\text{Mass of solution}}\times 10^9

Both the masses are in grams.

We are given:

Mass of arsenic = 164.5 ng = 164.5\times 10^{-9} g

1 ng=10^{-9} g

Volume of the sample = V = 15.3 cm^3

Density of the lake water sample ,d= 1.00 g/cm^3

Mass of sample =  M = d\times V=1.0 g/cm^3\times 15.3 cm^3=15.3 g

ppb=\frac{164.5\times 10^{-9} g}{15.3 g}\times 10^9=10.75

10.75 is the concentration of arsenic in the sample in parts per billion.

B)

Mass of arsenic in 1 cm^3  of lake water = \frac{164.5\times 10^{-9} g}{15.3}=1.075\times 10^{-8} g

Mass of arsenic in 0.710 km^3 lake water be m.

1 km^3=10^{15} cm^3

Mass of arsenic in 0.710\times 10^{15} cm^3 lake water :

m=0.710\times 10^{15}\times 1.075\times 10^{-8} g=7,633,660.130 g

1 g = 0.001 kg

7,633,660.130 g = 7,633,660.130 × 0.001 kg=7,633.660130 kg ≈ 7,633.66 kg

7,633.66 kg the total mass of arsenic in the lake that the company have to remove.

C)

Company claims that it takes 2.74 days to remove 41.90 kilogram of arsenic from lake water.

Days required to remove 1 kilogram of arsenic from the lake water :

\frac{2.74}{41.90} days

Then days required to remove 7,633.66 kg of arsenic from the lake water :

=7,633.66\times \frac{2.74}{41.90} days=499.19 days

1 year = 365 days

499.19 days = \frac{499.19}{365} years = 1.367 years\approx 1.37 years

It will take 1.37 years to remove all of the arsenic from the lake.

3 0
3 years ago
What are the equilibrium concentrations of pb2+ and f– in a saturated solution of lead(ii) fluoride if the ksp of pbf2 is 3.20×1
erica [24]
Answer is:  the equilibrium concentrations fluorine anion are 0.004 M and lead cation are 0.002 M.<span>
Chemical reaction: PbF</span>₂(aq) → Pb²⁺(aq) + 2F⁻(aq).<span>
Ksp = 3,2·10</span>⁻⁸.
[Pb²⁺] = x.
[F⁻] = 2[Pb²⁺] = 2x<span>
Ksp = [Pb²</span>⁺] · [F⁻]².
Ksp = x · 4x².
3,2·10⁻⁸ = 4x³.
x = ∛3,2·10⁻⁸ ÷ 4.
x = [Pb²⁺] = 0,002M = 2·10⁻³ M.
[F⁻] = 2 · 0,002M = 0,004 M = 4·10⁻³ M.

6 0
3 years ago
Read 2 more answers
Prepare a list of objects around you that are electroplated​
DedPeter [7]

Answer:

Hello! Some household items that are electroplated include kitchenware, such as metal pots and pans, door handles, mobile phones, and coins. An electroplated object is coated by electrolytic deposition with chromium, silver, or another metal.

8 0
2 years ago
Rank the nonmetals in each set from most reactive (1) to least reactive (3). Neon: Selenium: Fluorine
expeople1 [14]

The periodic trend of reactivity depends on whether the elements are metals or nonmetals. For metals, reactivity increases down a group and from right to left across a period. Nonmetals do the opposite. For nonmetals, reactivity increases up a group and from left to right across a period. Therefore, the rank is as follows:


Fluorine

Selenium

Neon


Hope this answers the question. Have a nice day.

3 0
3 years ago
Read 2 more answers
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