Today is a historic day! Why? Write a paragraph.

Which of the following descriptions

tangare [24]

Answer:

D

Explanation:

depending on the solid the shape will not change.

3 0

4 years ago

This is another word for microorganism.

nadezda [96]

Answer:

The another word for microorganism is microbe

7 0

3 years ago

Read 2 more answers

The arsenic in a 1.223 g sample of a pesticide was converted to H3AsO4 by suitable treatment. The acid was then neutralized, and

Vladimir79 [104]

Answer:

5.471% As₂O₃ in the sample.

Explanation:

...the reaction is: Ag+ + SCN- => AgSCN(s) Calculate the percent As2O3 in the sample. (F.W. As2O3 = 197.84 g/mol).

First, with the amount of KSCN we can find the moles of Ag in the filtrates. As we know the amount of Ag added we can know the precipitate of Ag and the moles of AsO₄ = 1/2 moles of As₂O₃ in the sample:

Moles KSCN = Moles Ag⁺ in the filtrate:

0.01127L * (0.100mol / L)= 0.001127moles Ag⁺

Total moles Ag⁺:

0.0400L * (0.0781mol/L) = 0.0031564 moles Ag⁺

Moles of Ag⁺ in the precipitate:

0.0031564 - 0.001127 = 0.0020294 moles Ag⁺

Moles AsO₄ = Moles As:

0.0020294 moles Ag⁺ * (1mol As / 3 moles Ag⁺) = 6.765x10⁻⁴ moles AsO₄

Moles As₂O₃:

6.765x10⁻⁴ moles AsO₄ * (1 mol As₂O₃ / 2 mol AsO₄) =

3.382x10⁻⁴ moles As₂O₃

Mass As₂O₃:

3.382x10⁻⁴ moles As₂O₃ * (197.84g/mol) = 0.0669g As₂O₃

Percent is:

0.0669g As₂O₃ / 1.223g sample * 100 =

<h3>5.471% As₂O₃ in the sample</h3>

7 0

3 years ago

What is the stoichiometric coefficient for oxygen when the following equation is balanced using the lowest whole-number coeffici

rodikova [14]

Answer:

Option (B) 7

Explanation:

C3H6O2(l) + O2(g) → CO2(g) + H2O(l)

To know the coefficient of O2 in the above equation, let us balance the equation.

The above equation can be balance as follow:

C3H6O2(l) + O2(g) → CO2(g) + H2O(l)

There are 3 atoms of C on the left side and 1 atom on the right side. It can be balance by putting 3 in front of CO2 as shown below:

C3H6O2(l) + O2(g) → 3CO2(g) + H2O(l)

There are 6 atoms of H on the left side and 2 atoms on the right side. It can be balance by putting 3 in front of H2O as shown below:

C3H6O2(l) + O2(g) → 3CO2(g) + 3H2O(l)

There are a total of 4 atoms of O on the left side and a total of 9 atoms on the right side. It can be balance by putting 7/2 in front of O2 as show below:

C3H6O2(l) + 7/2O2(g) → 3CO2(g) + 3H2O(l)

Multiply through by 2

2C3H6O2(l) + 7O2(g) → 6CO2(g) + 6H2O(l)

Now, the equation is balanced.

From the balanced equation above, the coefficient of O2 is 7.

7 0

3 years ago

Question 20 (3 points) Why is the moon visible? Question 20 options: It is on fire. It reflects sunlight. Earth lights it up. It

alexgriva [62]

20. Answer is "it reflects sunlight".

The moon is not a star as sun. Hence, moon can't produce light by itself. The only reason that we can see the moon is it reflects the sunlight. According to the distance from the sun to the moon, the light reflection can be varied.

21. Answer is "Jupiter".

Asteroid belt is a region which is located between Mars and Jupiter and consists of asteroids and minor planets. This asteroid belt has the 4% as the mass of our moon. Due to the Jupiter's strong gravity, it is prevented a forming of new planet by this asteroid belt.

22. Answer is "they are equal".

The period of revolution is the time which is taken by a mass to go completely one round around another mass. For moon, the period of revolution is 27 days.
The period of rotation is the time taken by a mass to complete one round around its own axis. It is about 27 days for moon.

23. Answer is "The moon is in Earth's shadow".

Lunar eclipse happens when Sun, Earth and moon are directly aligned each other and Earth is located in between the Sun and the moon. Then the moon is covered by the Earth's shadow.

24. Answer is "In a solar eclipse, it is Earth that is caught in the umbra of the moon. In a lunar eclipse, it is the moon that is caught in the umbra of Earth".

In total lunar eclipse, Earth is located between Sun and the moon and they are directly aligned to each other. The moon is totally covered with the Earth's shadow.
Total solar eclipse can be seen when the moon is located between sun and Earth by completely covering the sun.

25. According to the given choices, we can get "Apollo" as the answer.

Apollo 8 is the first manned mission to the moon. From that there were several manned mission including first manned landing on the moon. The Apollo program was conducted by USA.

5 0

3 years ago