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3 years ago

True or False? Elements in the same row have similar properties. Question 4 options: True False

Chemistry

2 answers:

Natasha2012 [34]3 years ago

6 0

4. false
5. true
6.valence electrons

I took the test

Hope this helps.

Gekata [30.6K]3 years ago

3 0

1) Answer is: False.

A period in the periodic table is a horizontal row. For example, sodium and chlorine are in third period and they have very different properties. Sodium is solid metal and chlorine is gaseous nonmetal. Elements in the same row have the same number of electron shells, but different proporties.

2) Answer is: True.

Group is a column of elements in the periodic table. For example, lithium and sodium are in 1 group of the periodic table and they both have one valence electron.

3) Answer is: valence electrons.

For example, electron configuration of oxygen atom: ₈O 1s² 2s² 2p⁴.

Oxygen atom has six valence electrons, so it is in 16 group of Periodic table of elements.

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The sum of the protons and neutrons in an atom is called the atomic number <br> True or False

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3 years ago

Which of these is an ethical issue associated with stem cell therapy? A) Implantation of stem cells into patients is unethical.

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List the following aqueous solutions in order of decreasing freezing point: 0.040 m glycerin (C3H8O3), 0.020 m potassium bromide

gogolik [260]

Answer:

Solutions from highest to lowest freezing point:

0.040 m glycerin = 0.020 m potassium bromide > 0.030 m phenol

Explanation:

$\Delta T_f=i\times K_f\times m$

$\Delta T_f$ = Depression in freezing point

i = van'T Hoff fcator

$K_f$ = Molal depression constant of solvent

m = molality of the solution

Higher the value of depression in freezing point at lower will be freezing temperature the solution.

1. 0.040 m glycerin

Molal depression constant of water = $K_f=1.86^oC/m$

i = 1 ( organic molecule)

m = 0.040 m

$\Delta T_{f,1}=1\times\times 1.86^oC/m\times 0.040 m$

$\Delta T_{f,1}=0.0744^oC$

2. 0.020 m potassium bromide

Molal depression constant of water = $K_f=1.86^oC/m$

i = 2 (ionic)

m = 0.020 m

$\Delta T_{f,2}=2\times\times 1.86^oC/m\times 0.020 m$

$\Delta T_{f,2}=0.0744^oC$

3. 0.030 m phenol

Molal depression constant of water = $K_f=1.86^oC/m$

i = 1 (organic)

m = 0.030 m

$\Delta T_{f,3}=1\times\times 1.86^oC/m\times 0.030 m$

$\Delta T_{f,3}=0.0558^oC$

$0.0744^oC=0.0744^oC > 0.0558^oC$

$\Delta T_{f,1}=\Delta T_{f,2}>\Delta T_{f,3}$

Solutions from highest to lowest freezing point:

0.040 m glycerin = 0.020 m potassium bromide > 0.030 m phenol

5 0

3 years ago

Which of the following is a physical

barxatty [35]

Answer:

C. solid iodine subliming into a gas

Explanation:

A physical change is a change that is reversible and can be reversed back into the original product. The atoms and molecules undergoes some rearrangement in the physical change. The process of change in the state of matters are placed under physical change. Solid iodine sublimes into purple gas on heating. The gas is then changed back to iodine crystals after being cooled. Hence, this is an example of a physical change.

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3 years ago