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2 years ago

Which of the below elements are part of a group? Feel free to use the periodic table.

Chemistry

2 answers:

LUCKY_DIMON [66]2 years ago

5 0

Answer:

B. Be, Mg, Ca, Sr

Explanation:

Be, Mg, Ca, Sr are parts of the alkaline Earth metal family/group. So they are the second most reactive elements following behind alkali metals. Furthermore, Be, Mg, Ca, Sr all have 2 valence electrons that lose them to form cations. They have low melting points, low boiling points, can conduct electricity, have high malleability and ductility.

Hope it helped!

gogolik [260]2 years ago

4 0

B. Be, Mg, Ca, Sr (hope this helps)

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2 years ago

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Which of the following statements is TRUE? Question 5 options: The emission spectrum of a particular element is always the same

amm1812

Answer:

All of the above are true

Explanation:

a) The emission spectrum of a particular element is always the same and can be used to identify the element: It's true since the emission spectrum for each element is unique. It has the same bright lines at the same wavelength. This feature is used to identify elements. For example, the study of the emission spectra of light arriving from stars allow us to identify the elements presents in the star because the light contains the emission spectra of those elements.

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3 years ago

Which of the following is a clue that something is pseudoscience?

adelina 88 [10]

D i think if not here’s this a collection of beliefs or practices mistakenly regarded as being based on scientific method

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3 years ago

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Triss [41]

Explanation:

For the first part,

Reaction equation:

N₂ + 3H₂ → 2NH₃

Given:

Number of moles of NH₃ = 6 moles

Unknown:

Number of moles of N₂ = ?

Solution:

N₂ + 3H₂ → 2NH₃;

From the reaction above, we solve from the known specie to the unknown. Ensure that the equation is balanced;

2 moles of NH₃ is produced from 1 mole of N₂

6 moles of NH₃ will be produced from $\frac{6}{2}$ mole of N₂

= 3moles of N₂

The number of moles of N₂ is 3 moles

ii.

Given parameters:

Number of moles of sulfur = 2.4moles

Molar mass of sulfur = 32.07g/mol

Unknown:

Mass of sulfur = ?

Solution:

The number of moles of any substance can be found using the expression below;

Number of moles = $\frac{mass}{molar mass}$

Mass of sulfur = number of moles of sulfur x molar mass

Insert the parameters and solve;

Mass of sulfur = 2.4 x 32.07 = 76.97g

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2 years ago

A pycnometer is a precisely weighted vessel that is used for highly accurate density determinations. Suppose that a pycnometer h

dexar [7]

Answer:

5.758 is the density of the metal ingot in grams per cubic centimeter.

Explanation:

1) Mass of pycnometer = M = 27.60 g

Mass of pycnometer with water ,m= 45.65 g

Density of water at 20 °C = d = $998.2 kg/m^3$

1 kg = 1000 g

$1 m^3=10^6 cm^3$

$998.2 kg/m^3=\frac{998.2 \times 1000 g}{10^6 cm^3}=0.9982 g/cm^3$

Mass of water ,m'= m - M = 45.65 g - 27.60 g =18.05 g

Volume of pycnometer = Volume of water present in it = V

$Density=\frac{Mass}{Volume}$

$V=\frac{m'}{d}=\frac{18.05 g}{0.9982 g/cm^3}=18.08 cm^3$

2) Mass of metal , water and pycnometer = 56.83 g

Mass of metal,M' = 9.5 g

Mass of water when metal and water are together ,m''= 56.83 g - M'- M

56.83 g - 9.5 g - 27.60 g = 19.7 g

Volume of water when metal and water are together = v

$v=\frac{m''}{d}=\frac{19.7 g}{0.9982 g/cm^3}=19.73 cm^3$

Density of metal = d'

Volume of metal = v' = $\frac{M'}{d'}$

Difference in volume will give volume of metal ingot.

v' = v - V

$v'=19.73 cm^3-18.08 cm^3=$

$v'=1.65 cm^3$

Since volume cannot be in negative .

Density of the metal =d'

= $d'=\frac{M'}{v'}=\frac{9.5 g}{1.65 cm^3}=5.758 g/cm^3$

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2 years ago