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nexus9112 [7]
3 years ago
12

Helium is in group 18 of the periodic table. How is helium different from the other elements in this group?

Chemistry
1 answer:
pishuonlain [190]3 years ago
7 0

Answer:

Helium is in group 18 of the periodic table. How is helium different from the other elements in this group? = Helium atoms have 2 valence electrons, while atoms of the other elements in the group all have 8 valence electrons.

An emission spectrum will occur when = An electron releases energy and falls back to a lower energy level.

Explanation:

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olganol [36]
Thomson saw the atom to be a spherical cloud of positive proton matter with electrons dispersed throughout it. Then the gold foil experiment is when Rutherford shot alpha particles at a sheet of gold foil and when there was deflection he concluded there was a dense part in the center of an atom with he called the nucleus made up of neutrons and protons.
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NaOH + HCl → NaCl + H2O
bearhunter [10]

Answer:

0.00496 g H2O

Explanation:

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3 years ago
Give me a hand,Solve this problem,Need everyone's help​
elixir [45]

Answer:

A. 8.8 g.

B. 5.3 g.

C. 449 g.

Explanation:

A. Determination of the mass of CO2.

Mole of CO2 = 0.2 mole

Molar mass of CO2 = 12 + (2×16)

= 12 + 32

= 44 g/mol

Mass of CO2 =?

Mole = mass /Molar mass

0.2 = mass of CO2 /44

Cross multiply

Mass of CO2 = 0.2 × 44

Mass of CO2 = 8.8 g

B. Determination of the mass of Na2CO3.

Mole of Na2CO3 = 0.05 mole

Molar mass of Na2CO3 = (2×23) + 12 + (3×16)

= 46 + 12 + 48

= 106 g/mol

Mass of Na2CO3 =?

Mole = mass /Molar mass

0.05 = mass of Na2CO3 /106

Cross multiply

Mass of Na2CO3 = 0.05 × 106

Mass of Na2CO3 = 5.3 g

C. Determination of the mass of Fe(OH)2.

Mole of Fe(OH)2 = 5 moles

Molar mass of Fe(OH)2 = 55.8 + 2(16 + 1)

= 55.8 + 2(17)

= 55.8 + 34

= 89.8 g/mol

Mass of Fe(OH)2 =?

Mole = mass /Molar mass

5 = mass of Fe(OH)2/89.8

Cross multiply

Mass of Fe(OH)2 = 5 × 89.9

Mass of Fe(OH)2 = 449 g.

8 0
3 years ago
The observation has to be made up and i can’t think of anything or a hypothesis who can help!
Setler79 [48]

Answer:the answer is hypothesis

Explanation: that’s the answer

8 0
4 years ago
Consider the combustion reaction for octane (C8H18), which is a primary component of gasoline.
DIA [1.3K]

Answer:

1.16 moles CO₂

Explanation:

To find the moles of CO₂, you need to (1) convert grams C₈H₁₈ to moles (via the molar mass) and then (2) convert moles C₈H₁₈ to moles CO₂ (via the mole-to-mole ratio from equation coefficients). It is important that the conversions/ratios are arranged in a way that allows for the cancellation of units. The final answer should have 3 significant figures like the given value.

Molar Mass (C₈H₁₈): 8(12.011 g/mol) + 18(1.008 g/mol)

Molar Mass (C₈H₁₈): 114.232 g/mol

2 C₈H₁₈ + 25 O₂ -----> 16 CO₂ + 18 H₂O
^                                    ^

16.6 g C₈H₁₈            1 mole            16 moles CO₂          
--------------------  x  -----------------  x  -------------------------  = 1.16 moles CO₂  
                              114.232 g          2 moles C₈H₁₈          

3 0
2 years ago
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