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3 years ago

Help me please I really need help and answer only if u know the answer

Chemistry

2 answers:

Lady bird [3.3K]3 years ago

5 0

The answer is the second one, The others make no logical sense.

Ahat [919]3 years ago

4 0

Answer:

They have similar DNA

Explanation:

DNA is what makes a reasons appearance

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What is the pressure of a 3.5 mmol sample of ethane (C2H6) gas contained in a 0.500 L flask at 298 K?

-BARSIC- [3]

P = nRT/V

P = 3.5 x 10^-3 x 0.082 x 298 /0.5

P = 0.171 m Hg

P = 171 mm Hg

hope this helps

8 0

3 years ago

Assuming that the bath contains 250.0 g of water and that the calorimeter itself absorbs a negligible amount of heat, calculate

Anvisha [2.4K]

Answer:

$-3272$ kJ/mol

Explanation:

Given and known facts

Mass of Benzene $= 0.187$ grams

Mass of water $= 250$ grams

Standard heat capacity of water $= 4.18$ J/g∙°C

Change in temperature ΔT $= 7.48$ °C

Heat

$=250 * 4.18 * 7.48\\=7816.6 \\=7.82$

Heat released by benzine is - 7.82 kJ

Now, we know that

$0.187$ grams of benzene release $= -7.82$ kJ heat

So, $1$ g benzine releases

$\frac{ -7.82 }{0.187}\\= -41.8$

kJ/g

$0.187 * \frac{1}{78.108}=0.00239$ mol C6H6

Heat released

$= \frac{-7.82}{ 0.00239}$

$=-3272$ kJ/mol

4 0

3 years ago

The element lead (pb) consists of four naturally occurring isotopes with atomic masses 203.97302,205.97444,206.97587, n 207.9766

Marina CMI [18]

The method of determining the most common isotope of lead is by determining the average atomic mass. The formula for determining the average atomic mass is:

$average atomic mass = \Sigma {percent abundance}\times {atomic mass}$

Substituting the values in the formula:

$average atomic mass = \frac{{203.97302}\times {1.4}+{205.9744}\times {24.1}+{206.97587}\times {22.1}+{207.97663}\times {52.4}}{100}$

$average atomic mass = \frac{285.562228+4963.984004+4574.166727+10897.975412}{100}$

$average atomic mass = \frac{20721.688371}{100} = 207.22 amu$

The most common isotope of lead is:

Lead - 207.22 amu

The atomic symbol of lead is $Pb$ . The atomic number of $Pb$ is 82.

So, the the most common isotope of lead can be written as:

$_{207.22}^{82}Pb$ and Lead - 207.22 amu.

3 0

3 years ago

How does a refracting telescope work?

Yakvenalex [24]

Answer:

Explanation:

because convex lenses bend light inward

7 0

3 years ago

A ball was massed in a dish. The total mass was 15.6 grams. Treball was placed in a

iVinArrow [24]

Answer:

14.57g

Explanation:

Given parameters:

Mass of dish + ball = 15.6g

Initial volume of water in the cylinder = 26.7mL

Final volume of water in the cylinder = 38.9mL

Mass of dish = ?

Unknown

Mass of the ball = ?

Solution;

Since the mass of ball and dish is 15.6g,

Mass of the ball =Mass of ball + dish - mass of the dish

Insert the parameters and solve;

Mass of the ball = 15.6g - 1.03g = 14.57g

3 0

3 years ago