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Dima020 [189]
3 years ago
11

How often do girls normally experience menstruation a.once every 30 days b. once every 29 c.once every 28 d.once every 27

Chemistry
2 answers:
Lana71 [14]3 years ago
6 0

Answer:

Once every 28 days

Explanation:

I am not 100% sure because i am not female but i do remember that in my health class it said it was once every 28 days

kramer3 years ago
5 0

Answer:

i think answer is a, every 30 days

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1. A gas has a volume of 45 L at a pressure of 140 kPa. What is the volume when
pishuonlain [190]

Answer:

The new volume of the gas is 21 L.

Explanation:

Volume of a gas is inversely proportional to its pressure at constant temperature such that,

V\propto \dfrac{1}{P}

or

P_1V_1=P_2V_2

We have,

V_1=45\ L\\\\P_1=140\ kPa \\\\P_2=300\ kPa

It is required to find V₂. Using above law or Boyle's law such that :

V_2=\dfrac{P_1V_1}{P_2}\\\\V_2=\dfrac{140\times 45}{300}\\\\V_2=21\ L

So, the new volume of the gas is 21 L.

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3 years ago
Pure acetic acid (hc2h3o2) is a liquid and is known as glacial acetic acid. calculate the molarity of a solution prepared by dis
Alexandra [31]
In order to find the molarity of the solution, we first require the moles of acetic acid added. For this,we need the mass which is:

Mass = volume * density

Mass = 50 * 1.05
Mass = 52.5 grams


Moles = mass / molecular weight

Moles = 52.5 / 60.05 
Moles = 0.874 mol

Next, we know that the molarity of a solution is:

Molarity = moles / liter
Molarity = 0.874 / 0.5

Molarity = 1.75 M
3 0
3 years ago
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The elements in the periodic table are not always represented by
alexandr402 [8]

Unnillium (101)

Unnilbium (102)

Unniltrium (103)

Unnilquadium (104)

Unnilpentium (105)

Unnilhexium (106)

Unnilseptium (107)

Unniloctium (108)

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6 0
2 years ago
100 ml of a 0.300 m solution of agno3 reacts with 100 ml of a 0.300 m solution of hcl in a coffee-cup calorimeter and the temper
Olin [163]

Answer:

100 ml of a 0.300 m solution of agno3 reacts with 100 ml of a 0.300 m solution of hcl in a coffee-cup calorimeter and the temperature rises from 21.80 °c to 23.20 °c. Assuming the density and specific heat of the resulting solution is 1.00 g/ml and 4.18 j/g ∙ °c respectfully, what is the ΔH°rxn?

39.013 kJ/mol.

Explanation:

AgNO3(aq) + HCl(aq) --------------> AgCl(s) + HNO3(aq)

We can calculate the amount of heat (Q) released from the solution using the relation:

Q = m.c.ΔT,

Where, Q is the amount of heat released from the solution (Q = ??? J).

m is the mass of the solution (m of the solution = density of the solution x volume of the solution = (1.0 g/mL)(200 mL) = 200 g.

c is the specific heat capacity of the solution (c = 4.18 J/g∙°C).

ΔT is the difference in the T (ΔT = final temperature - initial temperature = 23.20 °C - 21.80 °C = 1.4 °C).

∴ Q = m.c.ΔT = (200 g)(4.18 J/g∙°C)(1.4 °C) = 1170.4 J.

∵ ΔH°rxn = Qrxn/(no. of moles of AgNO₃).

Molarity (M) is defined as the no. of moles of solute dissolved in a 1.0 L of the solution.

M = (no. of moles of AgNO₃)/(Volume of the solution (L)).

∴ no. of moles of AgNO₃

               = (M)(Volume of the solution (L))

               = (0.3 M)(0.1 L) = 0.03 mol.

∴ ΔH°rxn

           = Qrxn/(no. of moles of AgNO₃)

            = (1170.4 J)/(0.03 mol)

            = 39013.33 J/mol

           = 39.013 kJ/mol.

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Although incineration can break down harmful chemicals, the byproduct is hazardous.
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