19. Who was the first female astronomer

A.Aristotle
B.En Hedu’Anna
C.Archimedes
D.Plato

Answer:

Temperate climates, otherwise known as meso-thermal climates, are cooler than subtropical climates, but warmer than polar climates. A continental moderate climate is another sub-type of temperate climates. These regions have hot, rainy summers and cold, dry winters.

Explanation:

Answer:

Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same.

Explanation:

Answer:

Changes can occur to physical properties of a substance, but the chemical composition of the substance remains the same.

Explanation:

im smart

Answer:

b sorry if im wrong

Explanation:

hope it helped

Answer:

stay the same

Explanation:

you would weigh less if u stood on a scale but you're still the same mass unless you chopped of a body part or something

Answer:

The expression of speed of light can be written as "c".

Explanation:

The speed of light is denoted by c. It is originated from the Latin word celeritas which means "speed".  Its value is 3×10⁸ m/s.

It is related to the frequency and wavelength as follow,

Speed of light = wavelength × frequency

c = λ × f

λ = c/f

This formula shows that both frequency ad wavelength are inversely related to each other.

Frequency is taken in Hz.

It is the number of oscillations, wave of light make in one second.

Wavelength is designated as "λ" and it is the measured in meter. It is the distance between the two crust of two trough.

Answer: Both are only physical changes.

Explanation:

Both are only physical changes.  

• The material, which takes part in the change is structurally similar after and before the change is known as the physical change.  

• The cloud formation is a physical change as when evaporation of water takes place  it goes into the air and produces cloud by the process of condensation. The same water goes back to earth by the process of precipitation and this get repeated again and again.  

• A chemical change takes place when formation of new substance takes place by combining two substances. In the case, when a magnet picks up iron in a junkyard, one is still having an iron and a magnet, no formation of substance is taking place. So it is a physical change.  

Thus, both the given processes are examples of only physical changes.

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Answer:

A

Explanation:

Tetrahedral

The term that describes the molecular structure is Tetrahedral. The correct option is A.

The molecular structure is the structure of the molecular compounds. It tells the presence of ions and bonds in a compound. It is the arrangement of atoms, groups, or ions in a molecule, as well as the quantity and distribution of chemical bonds.

The use and importance of molecular structure are comprehending Nature's complex design principles and blueprints depend on understanding molecular structure.

Perhaps we can start to imitate her lovely items more cheaply and with less negative environmental effects if we can comprehend her plans and fundamental materials. The given compound is tetrahedral.

Thus, the correct option is A. Tetrahedral.

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Answer:

Mg with 2 dots

Explanation:

Mg: as the valnce shell of Mg has 2 electrons only

presented by 2 dots

Protons

Protons are the subatomic particle that determines the identity of an element.

Answer:

Explanation:Protons and neutrons are located in the nucleus of an atom and determine the mass of an atom. Protons have a positive electrical charge and electrons have a negative electrical charge. Atoms that have the same number of protons and electrons do not have an electrical charge.

Answer:

2

Explanation:i did the test

Answer:

0.00505

Explanation:

You can google the answer or try to learn how to convert it

Moles of Fe₂O₃ formed : 1.95

A reaction coefficient is a number in the chemical formula of a substance involved in the reaction equation. The reaction coefficient is useful for equalizing reagents and products.

[tex]\tt 4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]

We find the limiting reactant from the ratio of the mole and the reaction coefficient

Fe ⇒ 3.9 : 4 = 0.975

O ⇒ 4.7 : 3 = 1.56

Because the ratio of Fe is smaller, then Fe becomes the limiting reactant

Reaction

4Fe + 3O₂ ⇒ 2Fe₂O₃

mol Fe₂O₃ from mol of Fe as limiting reactant

mol ratio Fe₂O₃ : Fe = 2 : 4, then mol Fe₂O₃ :

[tex]\tt =\dfrac{2}{4}\times 3.9=\boxed{\bold{1.95}}[/tex]

Explanation:

14 neutrons

Explanation: The mass number is the total number of protons and neutrons in a nucleus. The atomic number is the number of protons in the nucleus. →27−13=14 neutrons!

Answer: Because atoms cannot be created or destroyed in a chemical reaction, elements such as phosphorus (P 4) or sulfur (S 8) cannot be broken down into simpler substances by these reactions. Example: Water decomposes into a mixture of hydrogen and oxygen when an electric current is passed through the liquid

Explanation:

Answer:

elements because they are the simplest form of matter so they can't be broken

Explanation:

Hope this helps:)

12.01 amu

Work:

(12.000 × .9889) + (13.003 × .0111) = 12.01

Answer:

compound

Explanation:

Answer:

your answer would be compound

Answer:

Gravity

Explanation:

A planet is gravitationally pulled around the sun.

Answer:

beause of gravitys pull and because the atmosphere of the beyond lol also bcs this i hope this helps your welcome boo >3

Explanation:

Newton realized that the reason the planets orbit the Sun is related to why objects fall to Earth when we drop them. The Sun's gravity pulls on the planets, just as Earth's gravity pulls down anything that is not held up by some other force and keeps you and me on the ground.

Answer:

heat I think.....

During a change in state, energy is transferred in the form of heat.

Hence, Option (A) is correct.

When energy is added or removed to matter in the form of heat, it changes state to form a state of matter.

A state of matter is defined as one of the ways in which matter can interact with itself to form a homogeneous phase.

Therefore , During a change in state, energy is transferred in the form

of heat. Hence, Option (A) is correct.

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Answer:

The law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed.

Explanation:

Your answer should be- that in a chemical reaction mass is neither created nor destroyed.

Explanation:

Is that good?

Answer:

It depends on which element you are talking about. I appears that no element has an average atomic mass of that number. So, for the question, if it assumes that there are two isomers with 39 amu and 40 amu, then the 40 amu one would be more abundant. But again, there are different possible isotopes and I can't tell what the question wants.

Answer:

No, this is invalid. The term mono in front of monoatomic simply refers to the number of atoms that are present in a compound or simply by itself it has no relationship with respect to the overall charge of the compound.

Explanation:

For instance Ca is considered as a monoatomic ion but it has a charge of +2.

Answer: At STP, one mole (6.02 × 1023 representative particles) of any gas occupies a volume of 22.4 L (Figure below). A mole of any gas occupies 22.4 L at standard temperature and pressure (0°C and 1 atm).

Explanation:

That the answer

1 mole of a gas occupies 22.4 L at (0°C and 1 atm). It is the standard temperature and pressure.

Avogadro's hypothesis says that all gases have an equal number of particles at the same temperature and pressure.

The empty space between the particles makes up the majority of a gas's overall volume.

Due to this, the size of the particles themselves is nearly insignificant.

The volume of one mole of a gas at standard temperature and pressure is known as the molar volume.

Thus, the correct option is 0°C and 1 atm.

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Explanation:

A.

AgNO₃ + KCl → AgCl + KNO₃ (Already Balanced)

B.

H₂O + SO₃ → H₂SO₄ (Already balanced)

C.

2KI + Cl₂ → 2KCl + I₂

D.

2NaHCO₃ → Na₂CO₃ + H₂O + CO₂

E.

Zn + 2HCl → ZnCl₂ + H₂

F.

BaCl₂ + Na₂SO₄ → BaSO₄ + 2NaCl

G.

C₃H₈ + 5O₂ → 3CO₂ + 4H₂O

H.

2Al + 3CuCl₂ → 2AlCl₃ + 3Cu

Answer:

Explanation:

-------Choices  ---------------

Predict

Use variable

Plan and conduct investigations

Hypothesize

Measure

Classify and order

Record and display data

Use time and space relationships

Use numbers

=================

Selection:

These are in approximate order:

Plan and conduct investigations:  Design experiments that test the hypothesis.  E.g., see if any neutrons are reflected backwards.  If they are, the hypothesis needs to be changed.

Measure:  Do the work.  Calibrate the equipment and record everything.

Record and display data:  Publish the results and conclusions for peer review.  Seek other's input in order to generate general agreement that the data, procedure, and conclusions are warranted.

===

Use numbers?  Nah.  Not if they are not required to reach a conclusion.(e.g., the precipitate will be pink or the reaction will stink).

Use Time and Space Relationships:  Yes, but only if the hypothesis depends on them.

Classify and Order:  OK, especially if you are a biologist, but not always necessary.

Use variable:  usually, but what and how depends on the experiment.

Blame:  Place blame on the lab partner (Just kidding).