1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
vekshin1
2 years ago
11

Why is amniocentesis a more widely used test than cvs?

Chemistry
1 answer:
maw [93]2 years ago
4 0
Higher probability of loss. Chorionic villus sampling (CVS) and Amniocentesis (AC). The prenatal diagnosis technique can be done earlier in fetal development CVS (first trimester --> 10-13 weeks). AC (second trimester --> 16-20 weeks)

Thank you for posting your question here at brainly. I hope the answer will help you. Feel free to ask more questions.
You might be interested in
3. ¿Cuál de las siguientes operaciones es correcta para calcular el número de moles de hidrógeno necesarios para producir 6 mole
Aloiza [94]

Answer:

the answer is d that is 6×2/3

4 0
3 years ago
In the equation N2(g) + 3H2(g)--- 2NH3(g), how many liters of hydrogen
Delicious77 [7]

Answer:

30 L H2

Explanation:

  • 10 L N2 x <u>3 L H2</u> = 30 L H2

.                         1 L N2

Try to verify my answer, Stoichiometry is not easy for me.

3 0
2 years ago
Read 2 more answers
100.00 mL of 0.15 M nitrous acid (HNO2) are titrated with a 0.15 M NaOH solution. (a) Calculate the pH for the initial solution.
wolverine [178]

Answer:

a. pH = 2.04

b. pH = 3.85

c. pH = 8.06

d. pH = 11.56

Explanation:

The nitrous acid is a weak acid (Ka = 5.6x10⁻⁴) that reacts with NaOH as follows:

HNO₂ + NaOH → NaNO₂(aq) + H₂O(l)

a. At the beginning there is just a solution of 0.12M HNO₂. As Ka is:

Ka = [H⁺] [NO₂⁻] / [HNO₂]

Where [H⁺] and [NO₂⁻] ions comes from the same equilibrium ([H⁺] = [NO₂⁻] = X):

5.6x10⁻⁴ = X² / 0.15M

8.4x10⁻⁵ = X²

X = [H⁺] = 9.165x10⁻³M

As pH = -log [H⁺]

<h3>pH = 2.04</h3><h3 />

b. At this point we have HNO₂ and NaNO₂ (The weak acid and the conjugate base), a buffer. The pH of a buffer is obtained using H-H equation:

pH = pKa + log [NaNO₂] / [HNO₂]

<em>Where pH is the pH of the buffer,</em>

<em>pKa is -log Ka = 3.25</em>

<em>And [NaNO₂] [HNO₂] could be taken as the moles of each compound.</em>

<em />

The initial moles of HNO₂ are:

0.100L * (0.15mol / L) = 0.015moles

The moles of base added are:

0.0800L * (0.15mol / L) = 0.012moles

The moles of base added = Moles of NaNO₂ produced = 0.012moles.

And the moles of HNO₂ that remains are:

0.015moles - 0.012moles = 0.003moles

Replacing in H-H equation:

pH = 3.25 + log [0.012moles] / [0.003moles]

<h3>pH = 3.85</h3><h3 />

c. At equivalence point all HNO2 reacts producing NaNO₂. The volume added of NaOH must be 100mL. That means the concentration of the NaNO₂ is:

0.15M / 2 = 0.075M

The NaNO₂ is in equilibrium with water as follows:

NaNO₂(aq) + H₂O(l) ⇄ HNO₂(aq) + OH⁻(aq) + Na⁺

The equilibrium constant, kb, is:

Kb = Kw/Ka = 1x10⁻¹⁴ / 5.6x10⁻⁴ = 1.79x10⁻¹¹ = [OH⁻] [HNO₂] / [NaNO₂]

<em>Where [OH⁻] = [HNO₂] = x</em>

<em>[NaNO₂] = 0.075M</em>

<em />

1.79x10⁻¹¹ = [X] [X] / [0.075M]

1.34x10⁻¹² = X²

X = 1.16x10⁻⁶M = [OH⁻]

pOH = -log [OH-] = 5.94

pH = 14-pOH

<h3>pH = 8.06</h3><h3 />

d. At this point, 5mL of NaOH are added in excess, the moles are:

5mL = 5x10⁻³L * (0.15mol / L) =7.5x10⁻⁴moles NaOH

In 100mL + 105mL = 205mL = 0.205L. [NaOH] = 7.5x10⁻⁴moles NaOH / 0.205L =

3.66x10⁻³M = [OH⁻]

pOH = 2.44

pH = 14 - pOH

<h3>pH = 11.56</h3>
5 0
2 years ago
Which event would be impossible to explain by using John Dalton’s model of the atom?
geniusboy [140]

The scientist thought that the atom was the smallest particle in the universe is John Dalton. He established the atomic theory which consists of five; elements are made of extremely small particles called atoms, atoms of different element have different sizes, mass and physic – chemical properties, atoms cannot be divided further, destroyed or created, atoms can combine to form compounds and in chemical reaction, atoms can be combined, separated or rearranged. 

5 0
3 years ago
Read 2 more answers
How many moles are in 17.50g of SO2
monitta
The formula for mole is
n= Mass/Mol mass
Mol Mass: S=32
O2= 16(2)
—————
64 g/mol
N= 17.50 g
————— (cancel both g)
64 g/mol
= 0.27 mol is the answer
8 0
3 years ago
Other questions:
  • 5(1-8r)+8r the awnser
    8·2 answers
  • A gas at 155 kilopascals and 25 °c has an initial volume of 1 liter the pressure of the gas increases to 605 kilopascals as the
    7·1 answer
  • If you burn 22.6 g of hydrogen and produce 202 g of water, how much oxygen reacted
    8·1 answer
  • A scientist is studying two types of worms. Worm X has DNA identical to its parent. Worm Y has a combination of DNA from two par
    9·2 answers
  • A 1.803 g sample of gypsum, a hydrated salt of calcium sulfate, CaSO4 is heated at a temperature greater than 170 degree Celsius
    10·1 answer
  • Determine the mass in grams of 3.57 mol al
    12·1 answer
  • The equilibrium constant for the following reaction: H2(g) + Br2(g) ↔ 2HBr (g) is 1.65 x 103 at a certain temperature. Find the
    12·1 answer
  • What Type of chemical reaction is:<br> BaCl2 + 2 AgNO3 --&gt; 2 AgCl + Ba(NO3)2
    12·1 answer
  • A student needs to prepare 50.0 mL of 0.80 M aqueous H2O2 solution. Calculate the volume of 4.6 M H2O2 stock solution that shoul
    6·1 answer
  • Which ketone in each pair is more reactive?
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!