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2 years ago

PLEASE HELP!! 20 POINTS!

2 answers:

7 0

It's something to do with the weathering process. Eg. At night it's really cold, and in the day it's really hot. Because the temperature keeps changing dramatically day in and day out, the sand dunes start to be sort of hacked or re-shaped, or even formed.

Free_Kalibri [48]2 years ago

4 0

Hi there!

This "phenomenon" happens because of erosion caused by wind and deposition. Wind picks up grains of sand and deposits it when the sand encounters an obstacle (in this case, a sand dune or the like). Because the sand is not held in place like soil, the dunes are constantly changing, allowing for varied shapes and sizes of the dunes every year Eli and his family visit.

I hope that helps you out! Have a great day! :)

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A teacher had her students write down hypotheses about an experiment. Which is a valid hypothesis? (1 po If Earthquakes occur, t

Alja [10]

if people like the smell of burning wood, then they would not like the smell of gasoline

Explanation:

it's a supposition without any real truth to back it up

3 0

1 year ago

The correct way of making a soluiton of acid in water is to

Talja [164]

Explanation:

To add acid into water to dilute the solution but don't add water into acid it can explosive/ can burnt to the victim

7 0

3 years ago

s) Suppose we now collect hydrogen gas, H2(g), over water at 21◦C in a vessel with total pressure of 743 Torr. If the hydrogen g

Elenna [48]

This is an incomplete question, here is a complete question.

Suppose we now collect hydrogen gas, H₂(g), over water at 21°C in a vessel with total pressure of 743 Torr. If the hydrogen gas is produced by the reaction of aluminum with hydrochloric acid:

$2Al(s)+6HCl(aq)\rightarrow 2AlCl_3(aq)+3H_2(g)$

what volume of hydrogen gas will be collected if 1.35 g Al(s) reacts with excess HCl(aq)? Express your answer in liters.

Answer : The volume of hydrogen gas that will be collected is 1.85 L

Explanation :

First we have to calculate the number of moles of aluminium.

Given mass of aluminium = 1.35 g

Molar mass of aluminium = 27 g/mol

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

$\text{Moles of aluminium}=\frac{1.35g}{27g/mol}=0.05mol$

The given chemical reaction is:

$2Al(s)+6HCl(aq)\rightarrow 2AlCl_3(aq)+3H_2(g)$

As, hydrochloric acid is present in excess. So, it is considered as an excess reagent.

Thus, aluminium is a limiting reagent because it limits the formation of products.

By Stoichiometry of the reaction:

2 moles of aluminium produces 3 moles of hydrogen gas

So, 0.005 moles of aluminium will produce = $\frac{3}{2}\times 0.05=0.0750mol$ of hydrogen gas

Now we have to calculate the mass of helium gas by using ideal gas equation.

PV = nRT

where,

P = Pressure of hydrogen gas = 743 Torr

V = Volume of the helium gas = ?

n = number of moles of hydrogen gas = 0.075 mol

R = Gas constant = $62.364\text{ L Torr }mol^{-1}K^{-1}$

T = Temperature of hydrogen gas = $21^oC=[21+273]K=294K$

Now put all the given values in above equation, we get:

$743Torr\times V=0.075mol\times 62.364\text{ L Torr }mol^{-1}K^{-1}\times 294K\\\\V=1.85L$

Hence, the volume of hydrogen gas that will be collected is 1.85 L

8 0

3 years ago

Identify the double displacement reaction. 3Pb 2h 3PO 4 ⟶ 3H 2 Pb 3(PO 4) 2 2NO 2 ⟶ 2O 2 N 2 2NaBr Ca(OH) 2 ⟶ CaBr 2 2NaOH 2NH 3

IRISSAK [1]

Reaction 3 is the double displacement reaction.

Double displacement reaction occurs when the negatively and the positively charged ions of the compounds interchange their position when the new compound in the product is formed.

<h3>Which is a double displacement reaction?</h3>

In the <u>first reaction</u>, the element lead (Pb) is not an ion and no exchange of the cations or the anions occurs hence it is not a double displacement reaction.

In the <u>second reaction</u>, one compound is getting split into two new compounds and is a decomposition reaction.

In the <u>third reaction</u>, $\rm Br^{-}$ in $\rm 2NaBr$ and $\rm (OH)_{2}$ in $\rm Ca(OH)_{2}$ are anions and cations and exchanges their places to produce two new compounds $\rm CaBr_{2} + 2NaOH.$

In the <u>fourth reaction</u>, a single compound is generated as the result of the combination reaction and hence, it is not the double displacement reaction.

Therefore, $\rm 2NaBr + Ca(OH)_{2} \rightarrow CaBr_{2} + 2NaOH$ is the double displacement reaction.

Learn more about double displacement reaction here:

brainly.com/question/10091171

3 0

1 year ago

Chlorine has two stable isotopes, Cl-35 and Cl-37. If their exact masses are 34.9689 amu and 36.9695 amu, respectively, what is

natima [27]

Answer:

X(Cl-35) = 75.95% => Answer 'A'

Explanation:

34.9689·X(Cl-35) + 36.9695·X(Cl-37) = 35.45; X = fractional abundance

X(Cl-35) + X(Cl-37) = 1 ⇒ X(Cl-37) = 1 - X(Cl-25)

34.9689·X(Cl-35) + 36.9695(1 - X(Cl-35)) = 35.45

34.9689·X(Cl-35) + 36.9695 - 36.9695·X(Cl-35) = 35.45

Rearrange ...

36.9695·X(Cl-35) - 34.9689·X(Cl-35) = 36.9689 - 35.45

2.0006·X(Cl-35) = 1.5195

X(Cl-35) = 1.5195/2.0006 = 0.7595 fractional abundance

⇒ % abundance = 75.95%

3 0

3 years ago

Read 2 more answers