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Mrrafil [7]
3 years ago
5

The last element in any period always has:

Chemistry
2 answers:
sergeinik [125]3 years ago
8 0

Answer:

(A) eight electrons in the outermost energy level.

(C) the properties of a noble gas.

Explanation: option A and C are correct !

brilliants [131]3 years ago
4 0

Answer: The correct option is The properties of a noble gas.

Explanation: There are 7 periods in the periodic table.

The last element of each period are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe), Radon (Rn) and Ununoctium (Uuo).

  • The electronic configuration for Helium is 1s^2. For He, The outermost electrons are 2.
  • The electronic configuration for all the other elements is ns^2ns^6 ( where, n = 2, 3, 4, 5, 6 and 7 respectively). For all the other gases, the outermost electrons are 8.

All these elements have stable electronic configuration and are not reactive in nature. Hence, they are considered as noble gases.

Therefore, the last element of each period always have the properties of a noble gas.

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Which cell structure is found in animals, but not in plants?
andrezito [222]

Animal cells each have a centrosome and lysosomes, whereas plant cells do not. Plant cells have a cell wall, chloroplasts and other specialized plastids, and a large central vacuole, whereas animal cells do not.

4 0
3 years ago
Read 2 more answers
NEED HELP ASAP ITS DUE TODAY THESE QUESTIONS
beks73 [17]

1.

Density can be defined as the mass of the substance in unit volume.

Density = mass / volume

Hence, g/mL and kg/L can be used as the units of density.

Those units are interchangeable because when converting one unit into other one nothing will happen to the value.

That is because when converting the g into kg, you have to multiply the value by 1 x 10⁻³. When converting mL into L, you should again multiply the volume by 1 x 10⁻³. Then those 1 x 10⁻³ will cancel off and the original value will remain as same.

2.

Answer is 2.70 g/mL.

<em>Explanation;</em>

Mass of the block = 146 g

Volume of the block =  length x width x height

                                  = 6.0 cm x 3.0 cm x 3.0 cm

                                  = 54 cm³ = 54 mL

Density = mass / volume

            = 146 g / 54 mL

            = 2.70 g/mL

3.

Answer is  3.39 g/mL.

<em>Explanation;</em>

When immersing an object in a solution, the increased volume indicates the volume of that object.

Hence,

  Volume of the object = increased volume of water level

                                      = final volume - initial volume

                                      = 27.8 mL - 21.2 mL

                                      = 6.6 mL

Mass of the object = 22.4 g

Density = Mass / Volume

            = 22.4 g / 6.6 mL

            = 3.39 g/mL

4.

Accepted value is the value that scientists and community accept as true. This is a theoretical value.

But the measured value is the value that you obtain from doing experiments. This is the actual value.

If your measured value is more close to the accepted value, then your measured value is more precise. But, if your measured value is far away from accepted value means that your value is not precise and there may have some errors.

5.

Answers : Percent error is 9.11 %

                 The element which has 7.13 g/cm³ as density is Zinc (Zn).

<em>Explanation;</em>

Percent error can be calculated by using following formula.

% error = ( (measured value - accepted value) / accepted value ) x 100%

            = ( (7.78 g/cm³ - 7.13 g/cm³) / 7.13 g/cm³ ) x 100%

            = 9.11 %

6 0
3 years ago
Someone help me with chemistry on my account/page please :))
Gemiola [76]

Answer:

ok

Explanation:

5 0
3 years ago
0.25 mol of nitric acid is used to make a 0.10 M nitric acid solution. How many grams of solute was used?
Yanka [14]

Answer:

15.75 grams of HNO3 was used and dissolved in 2.5 liters of solvent, to make a 0.10 M solution

Explanation:

Step 1: Data given

Nitric acid = HNO3

Molar mass of H = 1.01 g/mol

Molar mass of N = 14.0 g/mol

Molar mass O = 16.0 g/mol

Number of moles nitric acid (HNO3) = 0.25 moles

Molairty = 0.10 M

Step 2: Calculate molar mass of nitric acid

Molar mass HNO3 = Molar mass H + molar mass N + molar mass (3*O)

Molar mass HNO3 = 1.01 + 14.0 + 3*16.0

Molar mass HNO3 = 63.01 g/mol

Step 3: Calculate mass of solute use

Mass HNO3 = moles HNO3 * molar mass HNO3

Mass HNO3 = 0.25 moles * 63.01 g/mol

Mass HNO3 = 15.75 grams

15.75 grams of HNO3 was used and dissolved in 2.5 liters of solvent, to make a 0.10 M solution

7 0
3 years ago
PLEASE HELP!!
Mandarinka [93]

Answer:

a. 211.7

Explanation:

Iron Pyrite reacts with Oxygen to produce Iron (II) Oxide and Sulphur (IV) Oxide.

The equation is as follows:

4FeS₂₍s₎ + 11O₂₍g₎ → 2Fe₂O₃₍s₎ + 8SO₂₍g₎

From the equation, 4 moles of FeS₂ produce 8 moles of SO₂.

Therefore the reaction ratio is 4:8 or 1:2

198.20 grams of FeS₂ into moles is calculated as follows:

Moles= Mass/RMM

RMM of FeS₂ is 119.9750g/mol.

Number of moles = 198.20/119.9750g/mol

=1.652 moles of FeS₂

The reaction ratio of FeS₂ to SO₂ produced is 1:2

Thus SO₂ produced = 1.652 moles×2/1=3.304 moles

The mass of SO₂ produced =Moles ×RMM

=3.304 moles ×64.0638 g/mol

=211.667 grams

=211.7g

8 0
3 years ago
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