How many planets did early astronomers know about?

Answer:its c and d

Explanation:

Answer:

earth

Explanation:

Answer:

The enthalpy of an endothermic reaction is positive, I believe.

''The enthalpy of an endothermic reaction is positive'' is the true statement about endothermic reaction

If a reaction absorbs more energy than releasing it, the reaction is considered as endothermic and enthalpy will be positive while on the other hand, if a reaction absorbs less energy and releasing more, the reaction is considered as exothermic and enthalpy will be negative.

So we can conclude that option C is the right answer.

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Answer:Matter can exist in one of three main states: solid, liquid, or gas. Solid matter is composed of tightly packed particles. A solid will retain its shape; the particles are not free to move around.

Explanation:

Answer:

Products

Explanation:

Answer:

Because the sun is low on the horizon, sunlight passes through more air at sunset and sunrise than during the day, when the sun is higher in the sky. More atmosphere means more molecules to scatter the violet and blue light away from your eyes.

Answer:

Glossopteris

Explanation:

Glossopteris is a fossil fern that helped support Wegener's hypothesis.

Hope this helps! Have a great day!

Answer:

The correct answer is -

1. D. mold

2. A. Cast

3. F. trace fossil

4. C. original material fossils

5. B. fossil record.

Explanation:

Mold is the impression of an organism in a rock that occurs due to the complete dissolving of the organism and only an impression left in sedimentary rocks.

The cast is a fossil copy of an organism in a rock that takes place when water-containing minerals fill the molds and creates a three-dimension copy of the fossil.

Trace fossils are the fossils that are preserved in such a manner that records of biological activity stored only instead of remains of plants or animals.

Storing originals animals or parts of the remaining such as tissue of an organism in natural form is known as original-material fossils.

Fossil records are the fossils ever found or discovered on the earth.

Answer:

2.040 mol CO

Explanation:

First, write out your reaction:

CO + O2 --> CO2

Balance the reaction:

2CO + O2 --> 2CO2

Now divide the 32.65 g O2 by the molar mass of O2 (32.00 g/mol) to get moles of O2. Then multiply by the mole ratio of 2 mol CO for every 1 mol O2 to get moles of CO needed to fully react.

32.65 g O2 / 32.00 g/mol = 1.020 mol O2

1.020 mol O2 • 2 mol CO / 1 mol O2 = 2.040 mol CO

Answer:

291.7167

Explanation:

The molar mass of Fe₂(CO₃)₃ is 291.714 g/mol.

To calculate the molar mass of Fe₂(CO₃)₃, we need to consider the atomic masses of the individual elements present in the compound.

The molar mass of each element is as follows:

Fe (iron): 55.845 g/mol

C (carbon): 12.011 g/mol

O (oxygen): 15.999 g/mol

Now, let's calculate the molar mass of Fe₂(CO₃)₃:

Molar mass = (2 × atomic mass of Fe) + (3 × atomic mass of C) + (9 × atomic mass of O)

Molar mass = (2 × 55.845 g/mol) + (3 × 12.011 g/mol) + (9 × 15.999 g/mol)

Molar mass = 111.69 g/mol + 36.033 g/mol + 143.991 g/mol

Molar mass = 291.714 g/mol

Therefore, the molar mass of Fe₂(CO₃)₃ is approximately 291.714 g/mol.

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#SPJ 2

Answer:

True

Explanation:

Because density of water decreases as volume increases as mass increases too.

Hence greater loads can be carried.

Answer:

The answer is 0.013413582325191. i assume you are converting between moles Potassium Chloride and gram. The molecular formula for Potassium Chloride is KCl. The SI base unit for amount of substance is the mole. 1 mole is equal to 1 moles Potassium Chloride, or 74.5513 grams.

Explanation:

Answer:

no H2O molecules are produced:)

Explanation:

Answer: 18 g of water occupies one mole and one mole contains Avagadro’s no. of molecules = 6.023*10^23 molecules .

Explanation:question says 72 g of water . 72 g of water occupies 4 moles.

So the no. of molecules in 72 g of water has 4*(6.023*10^23) molecules .

Answer:

c

Explanation:

Answer:

His third law states that for every action (force) in nature there is an equal and opposite reaction. In other words, if object A exerts a force on object B, then object B also exerts an equal and opposite force on object A. Notice that the forces are exerted on different objects.

Explanation:

Answer:

There would be 3 temperature changes and 2 phase transitions

Explanation:

The temperature of the material would first increase from T0 to Tm (its melting point)- This is one temperature change.

It would the change from solid to liquid at its melting point Tm.- This is one phase transition.

Its temperature would then increase from its melting point Tm to its boiling point Tv -This is another temperature change.

It would then change from liquid to gas at its boiling point Tv - This is another phase transition.

Finally, its temperature would then increase from its boiling point to T(f) - This is the third temperature change.

So, there would be 3 temperature changes and 2 phase transitions

Answer:

Explanation:

Maintaining a healthy, perennial plant cover.

Mulching.

Planting a cover crop – such as winter rye in vegetable gardens. ...

Placing crushed stone, wood chips, and other similar materials in heavily used areas where vegetation is hard to establish and maintain.???

Answer:

it's B(Energy source,conductor and receiver)

Answer:

Explanation:

Understand that a substance's specific heat (C) is a property that can be used to ... Calculate the heat required to melt 25.7 g of solid methanol at its melting point. ... How many moles of NH4NO3 must be dissolved in water so that 88.0 kJ of heat ... to vaporize 54.0 g of ethanol (C2H5OH) if AHvap for ethanol = 43.5. kJ/mol?

Answer:

Explanation:

The new pressure can be found by using the formula for Boyle's law which is

[tex]P_1V_1 = P_2V_2[/tex]

where

P1 is the initial pressure

P2 is the final pressure

V1 is the initial volume

V2 is the final volume

Since we're finding the new pressure

[tex]P_2 = \frac{P_1V_1}{V_2} \\[/tex]

We have

[tex]P_2 = \frac{13 \times 197000}{23} = \frac{2561000}{23} \\ = 111347.826...[/tex]

We have the final answer as

Hope this helps you

Answer:

There are 0.311 moles of  gas in the tank

Explanation:

Complete question

A 4.00g sample of gas is found to exert a pressure of 1.71 atm when confined in 3.60L container at a temperature of 241 K. Find the number of moles of the gas

Solution

As we know

[tex]PV = nRT[/tex]

where P is the pressure of the gas in atm

V is the volume in liters

n is the number of moles

R is the gas constant = 0.08206 L·atm/K·mol

and T is the temperature in Kelvin

Substituting the given values in above equation, we get -

[tex]1.71 * 3.60 = n * 0.08206 * 241\\n = 0.311[/tex]

There are 0.311 moles of  gas in the tank

Answer:

2.04moles

Explanation:

The balanced chemical equation of this reaction is given as follows:

Zn + 2HCl → ZnCl2 + H2

Based on the above balanced equation, 2 moles of hydrochloric acid (HCl) reacts to produce 1 mole of Zinc chloride (ZnCl2).

The question states that 148.8 grams HCl reacts. We need to convert this value to mole by using the formula;

mole = mass/molar mass

Molar mass = 36.46g/lol

mole = 148.8/36.46

mole = 4.08moles of HCl

Hence, if 2 moles of hydrochloric acid (HCl) reacts to produce 1 mole of Zinc chloride (ZnCl2).

Then, 4.08moles of HCl will react to produce (4.08 × 1/2)

= 2.04moles of ZnCl2.

Answer:

Explanation:

The name is of the compound is 3,3,4,4-tetramethylhexane.

Answer:

If there are fewer births than deaths, then the size of the population will decrease. Organisms in consumer populations get energy storage molecules from eating organisms in resource populations. The more energy storage molecules available to a population, the more the organisms in that population can reproduce.

A change to the green-leaf population caused the wee-bug population to change in size because wee-bug depends upon green leaves for their food.

It is a group of organism of the same species living in a particular area.

The increase or decrease in the population of organisms depends upon factors such as available resources and predator population.

The green leaf is the food resource for wee bugs hence if the green leaf population increase then the wee bug's population will also be increased.

Therefore, a change to the green-leaf population caused the wee-bug population to change in size because wee-bug depends upon green leaves for their food.

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Answer:

0.175mol

Explanation:

Molarity of a solution can be calculated thus:

Molarity (M) = number of moles (n) / volume (V)

According to the information provided in this question, volume of NH4OH = 0.125L, molarity = 1.4M

Using; Molarity = n/V

1.4 = n/0.125

n = 0.175mol

Answer:

1. B = 1.13M

2. A. 8.46%

3. D = 0.0199

Explanation:

1. Molarity of a a solution = number of moles of solute/ volume of solution in L

Number of moles of solute = mass of solute/molar mass of solute

Molar mass of NaC₂H₃O₂ = 82 g/mol, mass of NaC₂H₃O₂ = 245 g

Number of moles of NaC₂H₃O₂ = 245 g / 82 g/mol = 2.988 moles

Molarity of solution = 2.988 mols/ 2.65 L = 1.13 M

2. Percentage by mass of a substance = mass of substance /mass of solution × 100%

Mass of 2.65 L of water = density × volume

Density of water = 1 Kg/L = 1000 g/L; volume of waterb= 2.65 L

Mass of water = 1000 g/L × 2.65 L = 2650 g

Mass of solution = mass of water + mass of solute = 245 + 2650 =2895 g

Percentage by mass of NaC₂H₃O₂ = 245/2895 × 100% = 8.46%

3. Mole fraction of NaC₂H₃O₂ = moles of NaC₂H₃O₂/moles of solution

Moles of water = mass /molar mass

Mass of water = 2650 g; molar mass of water = 18 g/mol

Moles of water = 2650 g / 18 g/mol = 147.222 moles

Moles of solution = moles of solute + moles of water = 147.222 + 2.988 = 150.21

Moles of NaC₂H₃O₂ =2.988 moles

Moles fraction of NaC₂H₃O₂ =2.988/150.21 = 0.0199

Answer:

893 moles

Explanation:

An ideal gas at STP occupies 22.4 liters. Calculating Oxygen as if it were an ideal gas there are . 893 moles of Oxygen in 20.0 liters.