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3 years ago

12

28Which is true?

1 answer:

sergij07 [2.7K]3 years ago

8 0

28) All elements are made of atoms

29)Protons and Neutrons
-Electrons make up the outside of the Nucleus

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The movement of the earths plates is also called:

Ksenya-84 [330]

The movement of the Earth's plates is called Plate Tectonics. Hope this helps! :D

4 0

3 years ago

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Identify the mixture of powdered charcoal and powdered sugar and suggest a technique for separating their components

mihalych1998 [28]

A- Identify the mixture:
The mixture of powdered charcoal and powdered sugar is considered as a homogeneous mixture. This means that you cannot identify the components with naked eye as they are uniformly distributed in the mixture.

B- Separate components:
You ca separate the charcoal powder from the sugar powder using the following steps:
1- add water. Sugar will dissolve in water while charcoal won't.
2- filter the solution where the powdered charcoal will remain on the filter paper and the solution of powder will pass through.
3- boil the sugar solution (above 100 degrees celcius). The water will evaporate and the sugar will precipitate.

5 0

3 years ago

What amount of sucrose (C12H22O11) should be added to 5.83 mol water to lower the vapor pressure of water at 50 °C to 72.0 torr?

Triss [41]

Answer:

The amount of sucrose that must be added is 1.66 moles

Explanation:

Colligative property of lowering vapor pressure has this formula:

Vapor pressure of pure solvent (P°) - Vapor pressure of solution = P° . Xm

We have both vapor pressure (pure solvent and solution9, so let's determine the ΔP

ΔP = 92.6 Torr - 72 Torr = 20.6 Torr

Let's add the data in the formula

20.6 Torr = 92.6 Torr . Xm

Xm = Mole fraction of solute → (mol of solute/ mol of solute + mol of solvent)

Mol of solvent = 5.83 mol (data from the problem)

Therefore Xm = 20.6 Torr / 92.6 Torr → 0.222

Let's find out the moles of solute (our unknown value)

0.22 = moles of solute / moles of solute + 5.83 moles of solvent

0.222 (moles of solute + 5.83 moles of solvent) = moles of solute

0.222 moles of solute + 1.29 moles of solvent = moles of solute

1.29 moles of solvent = moles of solute - 0.222 moles of solute

1.29 moles = 0.778 moles of solute

1.29 / 0.778 = moles of solute → 1.66 moles

3 0

3 years ago

HELP PLEASE!! 20 POINTSS

Mrac [35]

The answer is 110., but round accordingly

3 0

2 years ago

An original sample of the radioisotope fluorine-21 had a mass of 80.0 milligrams. Only 20.0 milligrams of this original sample r

lyudmila [28]

<u>Answer:</u> The correct answer is Option 3.

<u>Explanation:</u>

All the radioisotope decay processes follow first order kinetics.

Rate law expression for first order kinetics is given by the equation:

$k=\frac{2.303}{t}\log\frac{a}{a-x}$

where,

k = rate constant = ?

t = time taken for decay process = 8.32 seconds

a = initial amount of the reactant = 80 mg

a - x = amount left after decay process = 20 mg

Putting values in above equation, we get:

$k=\frac{2.303}{8.32sec}\log\frac{80g}{20}\\\\k=0.166sec^{-1}$

The equation used to calculate half life for first order kinetics:

$t_{1/2}=\frac{0.693}{k}$

where,

$t_{1/2}$ = half life of the reaction = ?

k = $0.166sec^{-1}$

Putting values in above equation, we get:

$t_{1/2}=\frac{0.693}{0.166sec^{-1}}=4.16sec$

Hence, the correct answer is Option 3.

5 0

3 years ago

Read 2 more answers