Earnest Rutherford discovered that the nucleus is this

mel-nik [20]

The nucleus is the organelle present in eukaryotic cells with the main function in the control of all cell activities and maintaining the gene integrity. Namely, it contains the genetic material of the cell in the form of chromosomes (DNA molecules in complex with proteins). It is enclosed by the nuclear membrane which regulates the movement of proteins and RNA in and out of the nucleus.

4 0

3 years ago

An air stream enters a variable area channel at a velocity of 30 m/s with a pressure of 120 kPa and a temperature of 10°C. At a

nekit [7.7K]

Answer:

P₂= 74 kPa under constant density and ρ₂ = 1.06 kg/m³ (-38.6% of error compared with incompresible assumption) . Thus Bernoulli’s equation should not be applied

Explanation:

Assuming ideal gas behaviour of air , then

P*V= n*R*T = m / M * R *T

since

ρ= m/V = P*M /( R *T)

where

n= moles , V= volume , m= mass

ρ= density

P= pressure = 120 kPa= 120000 Pa

M= molecular weight of air = 0.21*32+0.79*28= 28.24 gr/mol = 0.02824 kg/mol

T= absolute temperature = 10°C + 273 = 283 K

R= ideal gas constant = 8.314 J/mol K

solving for ρ

ρ= P*M /( R *T) = 120000 Pa*0.02824 kg/mol/(8.314 J/mol K*283 K) = 1.47 kg/m³

then from Bernoulli's equation

P₁ + ρ*v₁²/2 = P₂ + ρ*v₂²/2

where 1 denotes inlet and 2 denotes other point , p = pressure and v= velocity . Then solving for p₂

P₁ + ρ*v₁²/2 = P₂ +ρ*P₂²/2

P₂= P₁ +ρ*v₁²/2 - ρ*v₂²/2 = P₁ +ρ/2*(v₁² - v₂²)

replacing values

P₂= P₁ +ρ/2*(v₁² - v₂²) = 120000 Pa + 1.47 kg/m³/2*[(30 m/s)²-(250 m/s)²] = 74724 Pa = 74 kPa

P₂= 74 kPa

then if the temperature remains constant

ρ₁= P₁*M /( R *T) and ρ₂= P₂*M /( R *T)

dividing both equations

ρ₂/ρ₁ = P₂/ P₁

ρ₂ = (P₂/ P₁)*ρ₁

then from Bernoulli's equation

P₁ + ρ₁*v₁²/2 = P₂ + ρ₂*v₂²/2

P₂ = P₁ + ρ₁*v₁²/2 - ρ₂*v₂²/2

therefore

ρ₂ = (P₂/ P₁)*ρ₁ = (P₁ + ρ₁*v₁²/2 - ρ₂*v₂²/2 ) /P₁ *ρ₁

P₁ * ρ₂ = P₁ *ρ₁ + ρ₁²*v₁²/2 - ρ₂*ρ₁ * v₂²/2

P₁ * ρ₂ + ρ₂*ρ₁ * v₂²/2 = P₁ *ρ₁ + ρ₁²*v₁²/2

ρ₂* (P₁ + ρ₁ * v₂²/2) = P₁ *ρ₁ + ρ₁²*v₁²/2

ρ₂ = (P₁ *ρ₁ + ρ₁²*v₁²/2)/(P₁ + ρ₁ * v₂²/2) = (P₁ + ρ₁*v₁²/2)/(P₁/ρ₁ + v₂²/2)

replacing values

ρ₂ = ( 120000 Pa + 1.47 kg/m³/2*(30 m/s)²)/(120000 Pa/1.47 kg/m³+1/2*(250 m/s)²)

ρ₂ = 1.06 kg/m³

the error of assuming constant ρ would be

e = (ρ₂ - ρ)/ρ₂= 1- ρ/ρ₂= 1- 1.47 kg/m³/1.06 kg/m³ = -0.386 (-38.6%)

thus Bernoulli’s equation should not be applied

8 0

3 years ago

A balloon of hydrogen is subjected to vacuum. The initial pressure and volume of hydrogen is 0.95 atm and 0.55 L. Calculate the

Scilla [17]

Answer:

0.43 atm

Explanation:

From the question given above, the following data were obtained:

Initial pressure (P₁) = 0.95 atm

Initial volume (V₁) = 0.55 L

Final volume (V₂) = 1.22 L

Final pressure (P₂) =?

The final pressure of the gas can be obtained by using the Boyle's law equation as follow:

P₁V₁ = P₂V₂

0.95 × 0.55 = P₂ × 1.22

0.5225 = P₂ × 1.22

Divide both side by 1.22

P₂ = 0.5225 / 1.22

P₂ = 0.43 atm

Therefore, the final pressure of the gas is 0.43 atm

7 0

3 years ago

There are 3.20 x 10^22 atoms of copper in the outer shell of pennies. How many grams of

Vesnalui [34]

Convert to moles first and then use the molar mass of copper to convert to grams

3 0

3 years ago

How many moles of h2 can be formed if a 3.25g sample of Mg reacts with excess HCl

kogti [31]

Answer:

0.134 moles of H₂ can be formed if a 3.25g sample of Mg reacts with excess HCl

Explanation:

The balanced reaction is:

Mg + 2 HCl → MgCl₂ + H₂

By stoichiometry of the reaction (that is, the relationship between the amount of reagents and products in a chemical reaction), the following amounts of moles react:

Mg: 1 mole
HCl: 2 moles
MgCl₂: 1 mole
H₂: 1 mole

Being:

Mg: 24. 31 g/mole
H: 1 g/mole
Cl: 35.45 g/mole

the molar mass of the compounds participating in the reaction is:

Mg: 24.31 g/mole
HCl: 1 g/mole + 35.45 g/mole= 36.45 g/mole
MgCl₂: 24.31 g/mole + 2*35.45 g/mole= 95.21 g/mole
H₂: 2*1 g/mole= 2 g/mole

Then, by stoichiometry of the reaction, the following quantities of mass participate in the reaction:

Mg: 1 mole* 24.31 g/mole= 24.31 g
HCl: 2 moles* 36.45 g/mole= 72.9 g
MgCl₂: 1 mole* 95.21 g/mole= 95.21 g
H₂: 1 mole* 2 g/mole= 2 g

Then you can apply the following rule of three: if by stoichiometry 24.31 grams of Mg form 1 mole of H₂, 3.25 grams of Mg how many moles of H₂ will they form?

$moles of H_{2} =\frac{3.25 grams of Mg*1 mole of H_{2} }{24.31 grams of Mg}$

moles of H₂= 0.134

0.134 moles of H₂ can be formed if a 3.25g sample of Mg reacts with excess HCl

7 0

3 years ago