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butalik [34]
3 years ago
5

Which of the following numbers count as exact numbers and do not count when determining significant figures in a calculation? 1.

Density: 3.7 g/mL 2. Volume: 1000 mL/L 3. Length: 2.54 cm/in 4. Speed: 65.2 km/hr 5. Number: 14 aardvarks 6. Mass: 38.741 g
Chemistry
1 answer:
rewona [7]3 years ago
4 0

Answer :

(1) Density do not count as exact number.

(2) Volume count as exact number.

(3) Length count as exact number.

(4) Speed do not count as exact number.

(5) Number count as exact number.

(6) Mass do not count as exact number.

Explanation :

Exact numbers : It is a defined or integer value which comes from counting numbers of objects.

They have an infinite number of significant figures.

For example : 12 eggs in a dozen, 1000 g in a kilogram and 2.54 cm in an inch.

Now we have to determine the following numbers count as exact numbers.

(1) Density : 3.7 g/mL

Density do not count as exact number.

(2) Volume : 1000 mL/L

Volume count as exact number.

(3) Length : 2.54 cm/in

Length count as exact number.

(4) Speed : 65.2 km/hr

Speed do not count as exact number.

(5) Number : 14 aardvarks

Number count as exact number.

(6) Mass : 38.741 g

Mass do not count as exact number.

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The oxidation number of I (iodine) decreases the in the described chemical reaction from 0 to -1.

Explanation:

We have the following chemical reaction:

I₂ + 2 KCl → KI + Cl₂

The following atoms have a change in the oxidation number:

I with a 0 oxidation number (in I₂) goes to I with -1 oxidation number (in KI) by receiving 1 electron.

Cl with a -1 oxidation number (in KCl) goes to I with 0 oxidation number (in Cl₂) by losing 1 electron.

Learn more about:

oxidation number

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7 0
2 years ago
Describe the procedure Bourouiba uses to study sneezes.
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Answer:

The Lydia Bourouiba is recorded is around more than the 100 sneezes and coughs cases.

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6 0
3 years ago
Which one would it be since covalent bond is not here :( please help meeee
timurjin [86]
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5 0
3 years ago
During _____, bonds between monomers are broken by adding water.
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3 0
3 years ago
Phenolphthalein has a pKa of 9.7 and is colorless in its acid form and pink in its basic form. calculate [In-}/{HIn} for the fol
zvonat [6]

Answer:

1.58x10⁻⁵

2.51x10⁻⁸

0.0126

63.10

Explanation:

Phenolphthalein acts like a weak acid, so in aqueous solution, it has an acid form HIn, and the conjugate base In-, and the pH of it can be calculated by the Handerson-Halsebach equation:

pH = pKa + log[In-]/[HIn]

pKa = -logKa, and Ka is the equilibrium constant of the dissociation of the acid. [X] is the concentrantion of X. Thus,

i) pH = 4.9

4.9 = 9.7 + log[In-]/[HIn]

log[In-]/[HIn] = - 4.8

[In-]/[HIn] = 10^{-4.8}

[In-]/[HIn] = 1.58x10⁻⁵

ii) pH = 2.1

2.1 = 9.7 + log[In-]/[HIn]

log[In-]/[HIn] = -7.6

[In-]/[HIn] = 10^{-7.6}

[In-]/[HIn] = 2.51x10⁻⁸

iii) pH = 7.8

7.8 = 9.7 + log[In-]/[HIn]

log[In-]/[HIn] = -1.9

[In-]/[HIn] = 10^{-1.9}

[In-]/[HIn] = 0.0126

iv) pH = 11.5

11.5 = 9.7 + log[In-]/[HIn]

log[In-]/[HIn] = 1.8

[In-]/[HIn] = 10^{1.8}

[In-]/[HIn] = 63.10

6 0
3 years ago
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