The Chinese first began recording astronomical observations about 2,000 years ago.


True
False

Answers

Answer 1
The answer is false

Related Questions

A sample of compound A (a clear, colorless gas) is analyzed and found to contain 4.27g carbon and 5.69g oxygen. A sample of compound B (also a clear, colorless gas) is analyzed and found to contain 5.19g carbon and 13.84g oxygen. Are these data an example of the law of definite proportions, the law of multiple proportions, or neither? What do these data tell you about substances A and B?

Answers

Answer:

law of multiple proportions

Explanation:

The law of multiple proportions states that, if two elements A and B, combine to form more than one chemical compound. Then the various masses of one element A, which combine separately with a fixed mass of element B are in  simple multiple ratio.

We can see that the ratio of oxygen that combines with carbon in the two compounds( A and B) is 1:2. This demonstrates the law of multiple proportions.

The substances A and B must be CO and CO2 respectively.

Which of these is smallest?
cells
atoms
matter
elements

Answers

Answer:

atoms

Explanation:

i hope that help you

Answer:

atoms

Explanation:

Suppose of nickel(II) bromide is dissolved in of a aqueous solution of potassium carbonate. Calculate the final molarity of nickel(II) cation in the solution. You can assume the volume of the solution doesn't change when the nickel(II) bromide is dissolved in it. Round your answer to significant digits.

Answers

The question is incomplete, the complete question is;

Suppose 1.87g of nickel(II) bromide is dissolved in 200.mL of a 52.0mM aqueous solution of potassium carbonate. Calculate the final molarity of nickel(II) cation in the solution. You can assume the volume of the solution doesn't change when the nickel(II) bromide is dissolved in it. Be sure your answer has the correct number of significant digits. The answer is needed in M.

Answer:

0.0428 M

Explanation:

The equation of the reaction is;

NiBr2 + K2CO3 → NiCO3 + 2KBr

Number of moles of NiBr2 = mass/molar mass = 1.87 g/218.53 g/mol =

8.557 *  10^-3 moles

Now, we know that the Ni^2+ comes from the NiBr2. Also, the concentration of Ni^2+ in NiBr2 = concentration of Ni^2+ in NiCO3

So,

Concentration of Ni^2+ = 8.557 *  10^-3 moles/0.2 L = 0.0428 M

How do you write 0.000157 in scientific notation

Answers

Answer:

1.57 × 10^-4

one point five seven times ten to the power of negative four

if you start with 4.3 moles of NH3, how many moles of NANH2 can be produced

Answers

Explanation:

Mole ratio of NH3 to NaNH2 = 2 : 2.

Moles of NaNH2 produced

= 4.3mol * (2/2) = 4.3mol.

You find yourself in a room with dark gray walls. Medeleev’s image says, “This element is essential for plant life to thrive and is found in heavy clay minerals and the ash from your campfire.” What element are these walls made from?

Answers

Answer:

juvn hgf   jb ujvi i  junk food sux

Explanation:

Consider a disubstituted aromatic compound. The parent name is benzene and there is a chloro and bromo substituent. Disubstituted benzenes can be described using the terms ortho, meta and para, depending on their relative distance from each other. The terms are often just abbreviated as o, m and p. In addition, the IUPAC name can use locant numbers instead of the descriptor. Br
Select the correct names for the structure.
1. 1-bromo-3-chlorobenzene
2. 3-bromo-1-chlorobenzene
3. meta-bromochlorobenzene
4. o-bromochlorobenzene
5. ortho-bromochlorobenzene
6. m-bromochlorobenzene

Answers

Answer:The correct names for the structure are:

--> 1. 1-bromo-3-chlorobenzene.

--> 3. meta-bromochlorobenzene.

--> 6. m-bromochlorobenzene.

Explanation:

Benzene is the simplest member of the aromatic hydrocarbons. It has a ring structure consisting of six carbon and six hydrogen atoms. This equally means that a benzene can have up to six substituents. One of the chemical properties is that benzene and other members of its series undergo substitution reaction whereby one or more of its six hydrogen atoms is replaced by monoatomic reagents.

Disubstituted benzene consists of two substituents which are described based on either numerical locants or specific words for the three possible forms.

The numerical locant method are used the same naming substitutes of other hydrocarbons. From the question, the numerical locant method was derived through using the following steps:

--> the functional group is benzene

--> there are two substituents which includes bromine( written as bromo) and chlorine ( written as chloro)

--> while placing the number, it's done alphabetically ('1-bromo' comes before '3-chloro') in a clockwise manner. This is to give chorine the lowest locant number.

The second naming method for a disubstituted benzene is the the ortho-, meta-, para- (or their singel letter equivalent) nomenclature method. This is only used for benzene structures.

--> ortho or O : this is used when the substituents are close to each other in the benzene ring.

--> meta or (m) : This is used when the substituents are separated by one carbon in the benzene ring.

--> para or (p): This is used when the substituents are across each other in the benzene ring

From the question, the bromine substituent is separated from the chlorine by one carbon atom, therefore it's meta-bromochlorobenzene or m-bromochlorobenzene.

Convert 8.876 × 10^12 m^2 to units of km^2.

Answers

Answer:

[tex]8.876\times 10^{18}\ km^2[/tex]

Explanation:

In this problem, we need to convert [tex]8.876 \times 10^{12}\ m^2[/tex] to km².

We know that,

1 km = 1000 m

⇒ 1 km² = 10⁶ m²

So,

[tex]8.876 \times 10^{12}\ m^2=8.876 \times 10^{12}\times 10^6\ km^2\\\\=8.876\times 10^{18}\ km^2[/tex]

So, [tex]8.876 \times 10^{12}\ m^2[/tex] is equal to [tex]8.876\times 10^{18}\ km^2[/tex].

It’s a simple question in Welding when you use a torch if you add a lot of oxygen to the fuel what happens does it burn faster or what I want to know

Answers

Answer:

Easy, the flame is smaller but burns hotter.

Explanation:

What happens to the reaction rate as a reactant gets used up?
A. The rate varies,
B. The rate goes down,
O c. The rate goes up.
D. The rate stays constant.

Answers

Answer: B. The rate goes down

Explanation:

(ILL GIVE 100 POINTS AND EDIT IT AND MARK BRAINLIEST) Examine the diagram of the cell cycle. Which label identifies the stage in which the DNA is copied and the cell grows? W X Y Z

Answers

Answer:

where is diagram. sorry.

In a disproportionation reaction, the disproportionate substance

A. has exactly one oxidation state.

B. has exactly two oxidation states.

C. has at least three oxidation states.

D. has either one or two oxidation states.

Answers

Answer:

The answer is C: has at least three oxidation states.

Explanation:

you're welcome

Answer:

C

Explanation:

got it right on Edge

Define the following Vocabulary words
1. Archae Bacteria
2. Bacteria
3. Eukarya Kingdom
4. Domain

Answers

1. Microorganisms that are similar to bacteria in size and simplicity of structure but radically different in molecular organization.
2. A member of a large group of unicellular microorganisms which have cell walls but lack organelles and an organized nucleus.
3. All the kingdoms of eukaryotic, including fungi, plantae, and animalia are placed in the domain eukarya.
4. Is the highest taxonomic rank in the hierarchical biological classification system, above the kingdom level.
Hope this helps

Help pls!!!!!!!!!!!!!

Answers

Answer:

3rd

Explanation:

Why do we see this star pattern in the winter, but not at other times of the year? (2 points)

Answers

Answer: We see constellations at different times of the year - spring, summer, fall, & winter. This occurs because the Earth is orbiting the Sun.

Explanation:

Help me please (btw I live in the U.S)

Answers

 Answer:

I live in the USA so the questions have been answered to reflect that accordingly.

1. The letter which represents summer where I live is Letter C

Explanation:

Letter C represents the June solstice which usually takes place between June 20 and June 21.

2. The letter which represents winter where I live is letter A.

Explanation:

Letter A represents the December solstice. Another name for this is Winter Solstice. This usually takes place in December for those living in the Northern Hemisphere like me. It is projected that this will take place on Tuesday, 21 December 2021.

Another name for this is Northern Hemisphere Winter Solstice as it marks the first day of winter.

3. The correct seasons for June Solstice are:

Northern Hemisphere: Summer Solstice

This projected to occur on Sunday, 20 of June 2020. It will be characterized by 1 hour of twilight and approximately 10 hours each of daylight and night time.

4. Southern Hemisphere: Summer solstice

This is anticipated on Tuesday, 21 December 2021. It will also be characterized by 1 hour of twilight and approximately 10 hours each of daylight and night time.

5. Northern Hemisphere: Autumnal (Fall) Equinox  

6. Southern Hemisphere:  Spring (Vernal) equinox  

7. December Solstice - Northern Hemisphere: Winter Solstice is the Day of the Year with the shortest amount of sunlight

8. December Solstice - Southern Hemisphere: Summer Solstice. This is the day of the year with the longest amount of sunlight

9. March Equinox - Northern Hemisphere: Spring (Vernal) Equinox. This is the start of spring.

10. March Equinox - Southern Hemisphere: Autumnal (Fall) Equinox. This is the start of Fall.

Cheers!

what is the chemical symbol for fluoride

Answers

Answer:  

I think F

Explanation:

The symbol for fluoride F

Carbon dioxide non examples? Please and catalyst non examples?

Answers

Answer:

I guess you mean by non element example. Non element examples have more than one elements. Carbon dioxide is a non element example since caebon dioxide has 2 oxygen atoms + 1 carbon atom = carbon dioxide.

I think catalyst is also a non element example because catalyst is inorganic which means that it is not a living thing. Since catalyst is in brass and brass is a non element example, I think catalyst is also a non element example.

Hope that helps, thank you !!

what do you think will happen if there is no coal.

Answers

Answer:

If coal and petroleum will get exhausted it will be very difficult for us to transport because most vehicles depends on petroleum, Transport on Earth will became complicated, and if coal will get exhausted we will lose an unique fossil fuel. Coal is used in various domestic and industrial purposes.


Determine the the nuclei indicated in blanks in the
right side when Radium (Ra-226) undergoes an
alpha decay
Ne
226/ 88
Ra -->
+

Answers

The daughter isotope  : Radon-222 (Rn-222).

Further explanation

Given

Radium (Ra-226) undergoes an  alpha decay

Required

The daughter nuclide

Solution

Radioactivity is the process of unstable isotopes to stable isotopes by decay, by emitting certain particles,  

alpha α particles ₂He⁴ beta β ₋₁e⁰ particles gamma particles ₀γ⁰ positron particles ₁e⁰ neutron ₀n¹

The decay reaction uses the principle: the sum of the atomic number and mass number before and after decay are the same

Radium (Ra-226) : ₈₈²²⁶Ra

Alpha particles : ₂⁴He

So Radon-226 emits alpha α particles ₂He⁴  , so the atomic number decreases by 2, mass number decreases by 4

The reaction :

₈₈²²⁶Ra ⇒ ₂⁴He + ₈₆²²²Rn

1.A cup of coffee with cream and sugar is a mixture (true or false)

2.give two examples of mixtures you see everyday in life

3.Look at the pictures of methods of separating a mixture and write down the correct names under each picture

(pictures are attached)

Answers

1. True because you mixed something with something else to make a substance:
2. Making tea you put the bag in the water, and noodles in broth
2. Water cycle and I don’t know what the other one is

Which color of light does a green object absorb?

Answers

Answer:

Magenta.

Explanation:

Color absorption is a process that occurs when a light wave strikes an object. When a light wave strikes an object it either absorbs color or transmits the color, or reflects the color. When a light wave strikes a green object, it absorbs a magenta color.

Magenta is a combination of red and blue light, therefore, the colors that the green object will absorb is red. blue, or magenta light.

in what way are these flowers similar from one another?​

Answers

What flowers are you talking about

Answer:

do you have names or pictures?

Explanation:

Please help asap! Giving brainliest to correct answer.

Three sections of the periodic table are labeled A, B, and C in the image below.

Which of the following statements is most likely true for an element present in section B?
Select one:

a. It is a highly reactive metal.

b. It is an inert gas at room temperature.

c. It may act as an insulator or a conductor.

d. It is a highly reactive liquid at room temperature.

Answers

Answer:

C. It may act as an insulator or a conductor.

Explanation:

Group B are the metalloids, so they have properties of both metals and nonmetals.

The statement which is most likely true for an element present in section B is: C. It may act as an insulator or a conductor.

A periodic table can be defined as an organized tabular array of all the chemical elements, which is typically arranged in order of increasing atomic number or number of protons (in rows).

In this diagram, the chemical element that is present in section B of the periodic table is a metalloid.

A metalloid can be defined as a chemical element that are typically intermediate between those of semiconductors, non-metals and metals.

Thus, a metalloid has both chemical and physical properties that are a combination of metals and non-metals or semiconductors.

In this context, the statement which is most likely true for an element present in section B is that it may act as an insulator or a conductor because it is a metalloid.

Read more: https://brainly.com/question/17482288

The increase in electro negativity when moving left to right on the periodic table can be explained by what?

Answers

Answer: Decrease in size

Explanation:

Electronegativity is defined as the property of an element to attract a shared pair of electron towards itself.

On moving across a period from left to right,   the size of an atom decreases because the electrons get added to the same shell and the nuclear charge keeps on increasing. Thus the electrons get more tightly held by the nucleus.

As, the size of an element decreases, the valence electrons come near to the nucleus. So, the attraction between the nucleus and the shared pair of electrons increases. Thus electronegativity increases.

During a chemistry lab exercise, a student isolates a compound at STP. In her
lab report, she has identified it as an ionic compound. If it is an ionic compound, it
will likely have a _________boiling point and be a _______ at STP.
Choose the answer with the words in the correct order that complete the
passage.
A. high; liquid
B. low; gas
C. high; solid
D. low; solid

please answer asap thank you !! :)

Answers

b i hope this help byee

Ionic compounds have a high boiling point and be a solid at STP.

What is ionic compound?

Ionic compounds are those compounds which are formed due to high electrostatic attraction between cations and anions.

Ionic compounds are generally present in the solid state because of the presence of strong ionic bond. And due to this rigid structure boiling point of ionic compounds are very high as they want more energy to break their bonds.

Therefor, at standard temperature pressure (STP) ionic compounds will likely have a high boiling point and be a solid at STP.

To learn more about ionic compounds, visit below link:

https://brainly.com/question/11638999

Which best describes a hydrate?

A.) It has water molecules bonded directly to it.
B.) It lacks water molecules ik it’s crystal lattice.
C.) It lacks hydrogen and oxygen atoms, which make up water.
D.) It has water molecules incorporated into its crystal lattice.

Answers

D is your best answer

Is the study of matter and energy complete, or do you think there’s still new information to discover?

Answers

Answer:

Physical science, in turn, can be divided into chemistry and physics. Chemistry is the study of matter and energy at the scale of atoms and molecules. ... Physics is the study of matter and energy at all scales—from the tiniest particles of matter to the entire universe but i dont really know if there is new information to discover

Explanation:

hope it help and if it doesnt sorry ;)

Hurry I need Now!!!In which biome would the climax species be reached most quickly following a fire?
A Taiga
B desert
C Grassland
D. deciduous forest
E tropical rain forest

Answers

Answer:

D. Deciduous Forest.

Explanation:

After looking at the schematics of the bubble, he finds that it holds 0.750 moles of gas at Standard Temperature and Pressure. Unfortunately for Rooster, helium gas is not sold by the mole, only by the liter. He needs to know how many liters of gas 0.750 moles of helium is.

Answers

Answer:

16.8 L

Explanation:

From the question given above, the following data were obtained:

Number of mole of He = 0.750 mole

Volume of He =?

Recall:

1 mole of any gas occupy 22.4 L at STP. This also implies that 1 mole of He occupies 22.4 L at STP.

Finally, we shall determine the volume occupied by 0.750 mole of He. This can be obtained as follow:

1 mole of He occupied 22.4 L at STP.

Therefore, 0.750 mole of He will occupy = 0.750 × 22.4 = 16.8 L at STP.

Thus, 0.750 mole of He is equivalent to 16.8 L

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