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3 years ago

3. Which of the following are isometries (rigid motions)? (Choose all that apply) (2 points)

Chemistry

2 answers:

Darya [45]3 years ago

7 0

Answer:

Explanation:

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vichka [17]3 years ago

5 0

Answer:

The answer is D.

Explanation:

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What is the final concentration of cl- ion when 250 ml of 0.20 m cacl2 solution is mixed with 250 ml of 0.40 m kcl solution? (as

serious [3.7K]

CaCl2 and KCl are both salts which dissociate in water when dissolved. Assuming that the dissolution of the two salts are 100 percent, the half reactions are:

CaCl2 ---> Ca2+ + 2 Cl-

KCl ---> K+ + Cl-

Therefore the total Cl- ion concentration would be coming from both salts. First, we calculate the Cl- from each salt by using stoichiometric ratio:

Cl- from CaCl2 = (0.2 moles CaCl2/ L) (0.25 L) (2 moles Cl / 1 mole CaCl2)

Cl- from CaCl2 = 0.1 moles

Cl- from KCl = (0.4 moles KCl/ L) (0.25 L) (1 mole Cl / 1 mole KCl)

Cl- from KCl = 0.1 moles

Therefore the final concentration of Cl- in the solution mixture is:

Cl- = (0.1 moles + 0.1 moles) / (0.25 L + 0.25 L)

Cl- = 0.2 moles / 0.5 moles

Cl- = 0.4 moles (ANSWER)

6 0

3 years ago

if the density of copper is 8.9g/cm^3 and the Volume of the sample is 23.4 mL what would be the mass?

Black_prince [1.1K]

Answer:

The mass of copper = 208.26 grams.

Explanation:

Density = mass / volume

8.9 = mass / 23.4

mass = 8.9 * 23.4

= 208.26 grams.

8 0

2 years ago

Hey pleaseeeeeeeeeeeeeeeeeeeeeeee

charle [14.2K]

Answer: B

Explanation:

6 0

3 years ago

Read 2 more answers

PLEASE HELP 30 POINTS PLS PLS

joja [24]

22-yes, they belong to the same group
23- they are metals
24-Atoms of group 1 elements all have one electron in their outer shell. This means Na and K have the same valence electrons.
25-Metals are solids at room temperature, therefore Na and K are solid.
26- mass number=A=235
Protons=z=92
Neutrons=mass number-protons
Neutrons=A-Z
Neutrons=235-92
Neutrons=143

8 0

2 years ago

A sample of nitrogen gas occupies a volume of 2.55 L when it is at 755 mm Hg and 23 degrees Celsius. Use this information to det

ivolga24 [154]

Answer: The number of moles of nitrogen gas are 0.1043 moles and the pressure when volume and temperature has changed is 461.6 mmHg

Explanation:

To calculate the amount of nitrogen gas, we use the equation given by ideal gas which follows:

$PV=nRT$

where,

P = pressure of the gas = 755 mmHg

V = Volume of the gas = 2.55 L

T = Temperature of the gas = $23^oC=[23+273]K=296K$

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

n = number of moles of nitrogen gas = ?

Putting values in above equation, we get:

$755mmHg\times 2.55L=n\times 62.364\text{ L.mmHg }mol^{-1}K^{-1}\times 296K\\\\n=\frac{755\times 2.55}{62.364\times 296}=0.1043mol$

To calculate the pressure when temperature and volume has changed, we use the equation given by combined gas law.

The equation follows:

$\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}$

where,

$P_1,V_1\text{ and }T_1$ are the initial pressure, volume and temperature of the gas

$P_2,V_2\text{ and }T_2$ are the final pressure, volume and temperature of the gas

We are given:

$P_1=755mmHg\\V_1=2.55mL\\T_1=23^oC=[23+273]K=296K\\P_2=?\\V_2=4.10L\\T_2=18^oC=[18+273]K=291K$

Putting values in above equation, we get:

$\frac{755mmHg\times 2.55L}{296K}=\frac{P_2\times 4.10L}{291K}\\\\P_2=\frac{755\times 2.55\times 291}{4.10\times 296}=461.6mmHg$

Hence, the number of moles of nitrogen gas are 0.1043 moles and the pressure when volume and temperature has changed is 461.6 mmHg

6 0

3 years ago

Read 2 more answers