In which of these situations is convection most likely the main form of heat transfer?Warm air from a heater on the first floor of a house moves to the upper floors.

The sides of a metal pan become hot when the pan is placed on a stove burner.

A person gets a sunburn from lying on the beach too long.

An ice cube melts when a person holds it in his hand.

Answers

Answer 1
Answer: In the first situation: the mechanism of covection is the main form of heat transfer when warm air from a heater moves around and upward.

In the case of the metal pan the mechanism of heat transfer is conduction.

In the case of sunburn the mechanism is radiation.

In the case of an ice cube melting in a hand, conduction is the most important mechanism.
Answer 2
Answer:

Answer:

An ice cube melts when a person holds it in his hand.

Explanation:


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On a mission to a newly discovered planet, an astronaut finds copper abundances of 69.97 % for 63Cu and 31.03 % for 65Cu. What is the atomic mass of copper for this location? The mass of 63Cu is 62.9300 amu . The mass of 65Cu is 64.9200 amu . Express your answer to two decimal places, and include the appropriate units.

Answers

Okay so to find the average atomic mass of copper in this location, you want to take the percentage of  abundance of an isotope and multiply (in decimal form) that by it's atomic mass, then you would add that with the product of the % of abundance of the other isotope times it's atomic mass.

(Side Note: Isotopes are  atoms of the element that have the SAME number of protons  but different number of neutrons, so they have different mass numbers. Also average atomic mass is the average of all the isotopes in an element - this number is the one that is shown on the periodic table of elements, not mass number).

Let me show you how to do this..

For the isoptope 63Cu I will first need to convert it's percentage of abundance into a decimal, because we don't use the percentage to multiply. 69.97% -> 0.6997. Now I am going to take it's atomic mass 62.9300 and multiply that by 0.6997.

62.9300*0.6997=44.0321

Now we still need to find calculate this  for the isotope 65Cu. To convert 31.03% to a decimal I will just move the decimal point two places to the left, to get 0.3103.
So I am going to take this and multiply it by 64.9200 the atomic mass of the isotope 65Cu.

64.9200*0.3103=20.1447

Add the two of these to get the average atomic mass..
20.1447 + 44.0321=64.1768


Enzymes are proteins that speed up chemical reactions in the body how do they workA. they increase the surface area of reactants
B.they increase the concentration of reactants
C.they decrease the concentration of products
D. They act as reactants

Answers

The answer would be D, Enzymes are soluble protein molecules that can speed up chemical reactions in cells. These reactions include respiration, photosynthesis and making new proteins. For this reason enzymes are sometimes called biological catalysts.

Answer:

D) They act as reactants

Explanation:

I took the test.

Hope this helps!!

The liquid-vapor equilibrium of a substance can be disturbed by cooling the substance.TRUE

FALSE

Answers

The statement "The liquid-vapor equilibrium of a substance can be disturbed by cooling the substance" is false. The substance must be heated in order to get the vapor phase of that substance.

Mass of 2.88x10^-4 mol of ascorbic acid

Answers

Molar mass C₆H₈O₆ = 176.12 g/mol

1 mole ------------------ 176.12 g
2.88x10⁻⁴ mole -------  ?

mass = 2.88x10⁻⁴ * 176.12 / 1

mass ≈ 0.05072 g

hope this helps!

Which atom in the ground state has a partially filled second electron shell?hydrogen atom
lithium atom
potassium atom
sodium atom

Answers

The atoms having partially filled shells have orbitals with electrons half or less than the number of electrons that can be accomodated in it.  The atom which has a partially filled second electron shell in the ground state is lithium.

What is lithium?

Lithium is 3rd element in periodic table and thus having 3 electrons in it. The main shell electronic configuration of lithium is written as K=2, L=1. Thus the second shell L has only one electron and it is said to be partially filled.

The element hydrogen is having only one electron located in the K shell and it have o more shells which are filled.

The elements sodium and potassium are first group elements sodium with 11 electrons and potassium atom with 19 electrons. Both are having 3 main shells and one electron in the last shell. Thus their second shell is completely filled.

Hence, the atom which have partially filled second electron shell in the ground state among the following is lithium. Thus, option B is correct.

To find more about lithium, refer the link below;

brainly.com/question/27642226

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Atoms have electrons filled in energy shells.
1. H - hydrogen atom has one electron in the First energy shell. Therefore hydrogen has a partially filled first energy shell

2.Li - Li electron configuration is 2,1
The outermost energy shell is the second energy shell in which there is only one electron
Therefore the second energy shell is partially filled. This is the correct answer

3. K - electron configuration is 2,8,8,1
The outermost energy shell is the fourth energy shell which is partially filled. The second energy shell is completely filled

4.Na - electron configuration is 2,8,1
The outermost energy shell is the third energy shell which is partially filled
Second energy shell is completely filled

From the given options Li is the only element with a partially filled second energy shell
Answer is Li

The longer the bond, the smaller the bond enthalpy. the longer the bond, the smaller the bond enthalpy. false true

Answers

True

As the shorter the bond, the stronger it is hence more energy will be required to overcome this bond

Final answer:

The statement 'The longer the bond, the smaller the bond enthalpy' is true as bond length and bond enthalpy have an inverse relationship. As bond strength increases (with an increase in electron pairs in the bond), bond length decreases. So longer bonds, indicating weaker bonding, have smaller bond enthalpies.

Explanation:

The statement 'The longer the bond, the smaller the bond enthalpy' is true. The bond length and bond enthalpy have an inverse relationship. As the strength of a bond increases with the increase in the number of electron pairs, the bond length decreases. Thus, triple bonds are generally stronger and shorter than double bonds between the same two atoms, and by the same logic, double bonds are stronger and shorter than single bonds.

For example, if we consider the bonds between carbon and various atoms in a group, we find the bond strength typically decreases as we move down the group - C-F has a bond enthalpy of 439 kJ/mol, C-Cl has 330 kJ/mol, and C-Br is at 275 kJ/mol.

The bond energy, essentially the enthalpy required to break the bond, is a representation of its strength. Thus, a longer bond, indicating weaker bonding, will have a smaller bond enthalpy.

Learn more about Bond Enthalpy here:

brainly.com/question/29633366

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