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2 years ago

If an emergency vehicle passes you in traffic, just as it passes you the pitch of

1 answer:

3 0

If an emergency vehicle passes you in traffic, just as it passes you the pitch of the siren changes as it approaches, the siren’s pitch sounds higher than when it is moving away from you.the frequency increases as the siren is moving toward you, and decreases as it is moving away, is correct

This change is a common physical demonstration of the Doppler effect.

<h3>What is Doppler effect ?</h3>

This effect refers to the increase in the frequency of sound, as the source and observer move toward (or away from) each other.

The effect causes the sudden change in pitch noticeable in a passing siren.

Hence Option (B) i.e, the frequency increases as the siren is moving toward you, and decreases as it is moving away, is correct

Learn more about Doppler' effect here ;

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What did rutherfords gold foil experiment help him conclude

Naya [18.7K]

It allowed him to realize that the mass of an atom is concentrated at its center because the atoms mostly went through the foil but some were deflected. He also realized that an atom probably wasn't just empty space and scattered electron and it had a positive center.

6 0

3 years ago

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A chemist adds 26.5g of ammonium chloride to 10g of sodium hydroxide, which follows the reaction below. Assuming the reaction go

4vir4ik [10]

Answer : The amount of reactant left in excess is 13.1075 grams.

Explanation : Given,

Mass of $NH_4Cl$ = 26.5 g

Mass of $NaOH$ = 10 g

Molar mass of $NH_4Cl$ = 53.5 g/mole

Molar mass of $NaOH$ = 40 g/mole

First we have to calculate the moles of $NH_4Cl$ and $NaOH$ .

$\text{Moles of }NH_4Cl=\frac{\text{Mass of }NH_4Cl}{\text{Molar mass of }NH_4Cl}=\frac{26.5g}{53.5g/mole}=0.495moles$

$\text{Moles of }NaOH=\frac{\text{Mass of }NaOH}{\text{Molar mass of }NaOH}=\frac{10g}{40g/mole}=0.25moles$

Now we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

$NH_4Cl+NaOH\rightarrow NH_4OH+NaCl$

From the balanced reaction we conclude that

As, 1 mole of $NaOH$ react with 1 mole of $NH_4Cl$

So, 0.25 moles of $NaOH$ react with 0.25 moles of $NH_4Cl$

From this we conclude that, $NH_4Cl$ is an excess reagent because the given moles are greater than the required moles and $NaOH$ is a limiting reagent and it limits the formation of product.

Moles of remaining excess reactant = 0.495 - 0.25 = 0.245 moles

Now we have to calculate the mass of $NH_4Cl$ .

$\text{Mass of }NH_4Cl=\text{Moles of }NH_4Cl\times \text{Molar mass of }NH_4Cl$

$\text{Mass of }NH_4Cl=(0.245mole)\times (53.5g/mole)=13.1075g$

Therefore, the amount of reactant left in excess is 13.1075 grams.

5 0

3 years ago

What volume of 0.25 mol/L solution of lead(II)nitrate would be required to form 500mL of a 0.15 mol/L solution of lead(II)nitrat

mafiozo [28]

To solve this we use the equation,

<span>where M1 is the concentration of the stock solution, V1 is the volume of the stock solution, M2 is the concentration of the new solution and V2 is its volume.</span>

0.25<span> M x V1 = 0.15 M x .500 L</span>

5 0

4 years ago

Which equation shows conservation of atoms? Group of answer choices 2 H2 + 2 O2 ---> H2O 2 H2 + O2 ---> 2 H2O H + O ---&gt

Harman [31]

<h3>Answer:</h3>

2 H₂ + O₂ → 2H₂O

<h3>Explanation:</h3>

The equation that shows the conservation of atoms is the balanced one.
In this case, the balanced equation is;

2 H₂ + O₂ → 2H₂O

Because it has 4 hydrogen atoms and 2 oxygen atoms on both sides of the equation.

Chemical equations are balanced to obey the law of conservation of mass that requires the mass of the reactant to be equal to the mass of the products.
Balancing chemical equations makes the number of atoms of each element in the equation equal, thus conserving the mass in the chemical reactions.

7 0

3 years ago

A flask has a mass of 78.23 g when empty and 593.63 g when filled with water. When the same flask is filled with concentrated su

ivanzaharov [21]

Answer:

1.84 g/cm³

Explanation:

A flask has a mass of 78.23 g when empty and 593.63 g when filled with water. The mass of water is:

m(water) = 593.63 g - 78.23 g = 515.4 g

The density of water is 1.00 g/cm³. The volume of water (and the flask) is:

515.4 g × (1 cm³/1.00 g) = 515 cm³

When the same flask is filled with concentrated sulfuric acid, H₂SO₄, its mass is 1026.57 g. The mass of H₂SO₄ is:

m(H₂SO₄) = 1026.57 g - 78.23 g = 948.34 g

948.34 g of sulfuric acid occupy a volume of 515 cm³. The density of sulfuric acid is:

ρ = 948.34 g / 515 cm³ = 1.84 g/cm³

3 0

3 years ago

Read 2 more answers