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3 years ago

QUestion 6 and 7

2 answers:

8 0

#6: The living organisms in an ecosystem can be divided into three categories: producers, consumers and decomposers. They are all important parts of an ecosystem.

#7: Nature has its own recycling system: a group of organisms called decomposers. Decomposers feed on dead things: dead plant materials such as leaf litter and wood, animal carcasses, and feces. They perform a valuable service as Earth's cleanup crew

HOPE THIS HELPS

Allisa [31]3 years ago

3 0

#7 decompsers eat on the dead. without decomposers dead leaves, dead animals and dead insects would pile up everywhere

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aev [14]

Answer:

5. An element's mass number tells the number of protons in its nucleus.

Atomic

6. Negatively charged particles in an atom are called electrons.

True

7. The cloud model of the atom describes the location of electrons as specific orbits around the nucleus.

Bohr

8. Atoms with the same number of protons but different numbers of neutrons are called isomers.

Isotopes

9. The sum of the protons and neutrons in an atom is called the atomic number.

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10. An object that helps explain ideas about the natural world is called a model.

True

11. Mendeleev arranged his periodic table in order of increasing atomic number.

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12. The rows in the periodic table are called periods.

True

13. Moving across the periodic table from left to right, one finds, in order, metals, then gases, then nonmetals.

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14. Another name for a period is a family.

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15. On the periodic table, elements in the same column have similar properties.

True

Explanation:

4 0

3 years ago

Calculate the energy required to ionize a hydrogen atom to an excited state where the electron is initially in the n = 5 energy

SVETLANKA909090 [29]

. The energy of shells in a hydrogen atom is calculated by the formula E = -Eo/n^2 where n is any integer, and Eo = 2.179X10^-18 J. So, the energy of a ground state electron in hydrogen is:

E = -2.179X10^-18 J / 1^2 = -2.179X10^-21 kJ

Consequently, to ionize this electron would require the input of 2.179X10^-21 kJ

2. The wavelength of a photon with this energy would be:

Energy = hc/wavelength

wavelength = hc/energy

wavelength = 6.626X10^-34 Js (2.998X10^8 m/s) / 2.179X10^-18 J = 9.116X10^-8 m

Converting to nanometers gives: 91.16 nm

3. Repeat the calculation in 1, but using n=5.

4. Repeat the calculation in 2 using the energy calculated in 3.

7 0

3 years ago

Read 2 more answers

HELP! me please help with this science assignment

Elina [12.6K]

I’m not sure about the rest but 4 is families

7 0

3 years ago

Read 2 more answers

Identify the limiting reagent and the moles of urea, (NH2)2CO(aq), produced given the following balanced chemical reaction and i

FinnZ [79.3K]

Answer:

Limiting reagent: NH3

moles of Urea = 0.45 moles

Explanation:

To do this, all we need to do is to see the balanced reaction which is:

2NH3 + CO2 ----------> (NH2)2CO + H20

Now, the leading numbers in the molecules mean in other words, the theorical moles that are needed to get this reaction.

So according to the reaction, 2 moles of NH3 reacts with 1 mol of CO2. Now, let's see how many moles do we actually have with the initial data:

moles of NH3 = 15.33/17.03 = 0.9 moles

moles of CO2 = 0.6 moles

Now that we have the moles, let's see which is the limiting reagent:

If:

2 NH3 -------> 1 CO2 then:

0.9 -----------> X

Solving for X:

X = 0.9 * 1 / 2 = 0.45 theorical moles of CO2

And we have 0.6 moles of CO2, which mean that we have in excess the CO2, therefore, the limiting reagent is the NH3. Let's prove it:

2NH3 -------> 1 CO2

X ----------> 0.6 moles

X = 0.6 * 2 / 1 = 1.2 theorical moles of NH3

And we have 0.9 moles of NH3. So this is a proof that NH3 is the limiting reagent as we state before.

As the NH3 is the limiting reagent, this means that in the reaction all the moles of NH3 will be consumed in the reaction and then, it will produce moles of urea.

Remanent moles of CO2 = 0.6 - 0.45 = 0.15 moles of CO2

moles of NH3 at the end of reaction: 0

moles of urea = 0.45 moles

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3 years ago

Intermolecular hydrogen bonding plays an important role in the structure of polymers.

gladu [14]

True
step by step explanation:

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3 years ago