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rewona [7]
3 years ago
6

The electronic arrangement of an atom shows how electrons are distributed across the different energy levels. Which of the follo

wing elements is represented by the electron arrangement 2, 8, 18, 6?
А Сa
B. Mg
C. S
D Se
E. Ga
Chemistry
1 answer:
bazaltina [42]3 years ago
5 0

Answer:

The answer is D which is Selenium

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A travel mug of 91∘C coffee is left on the roof of a parked car on a cold winter day. The temperature of the coffee after t minu
GREYUIT [131]

Answer: A

Explanation:

3 0
3 years ago
What is the reduction half equation of Fe(s)+ 2 HC2H3O2(aq) → Fe(C2H3O2)2(aq) + H2(g)
Sonbull [250]

Answer:

2 H⁺ + 2e = H₂    ( reduction )

Explanation:

Fe( s ) + 2 CH₃COOH = Fe ( OOCCH₃ ) ₂ + H₂

Fe( s ) = Fe⁺² + 2e     ( oxidation )

2 H⁺ + 2e = H₂    ( reduction )

4 0
3 years ago
Calculate the grams of sodium hydroxide formed when 2.24 moles of sodium oxide react with water
Romashka [77]
The balanced reaction is 
Na2O + H2O --> 2NaOH

If 2.24 moles of sodium oxide react, that means 4.48 moles of NaOH is formed as it is a 1 to 2 stoichiometric relationship.

Now we multiply by the molar mass to get grams.

4.48 moles NaOH * (39.997 grams/1 mole) = 179.2 grams

Your answer is 179. grams.
6 0
3 years ago
How do you work out question 1a?
Sliva [168]

Answer:

-125 kJ

Explanation:

You calculate the energy required to break all the bonds in the reactants. Then you subtract the energy to break all the bonds in the products.

                     H₂C=CH₂   +    H₂ ⟶    H₃C-CH₃

Bonds:       4C-H + 1C=C     1H-H     6C-H + 1C-C

D/kJ·mol⁻¹:  413       612        436       413      347

The formula relating ΔHrxn and bond dissociation energies (D) is

ΔHrxn = Σ(Dreactants) – Σ(Dproducts)

(Note: This is an exception to the rule. All other thermochemical reactions are “products – reactants”. With bond energies, it’s “reactants – products”. The reason comes from the way we define bond energies.)

<em>For the reactant</em>s:

Σ(Dreactants) = 4 × 413 + 1 × 612 + 1 × 436 = 2700 kJ

<em>For the products:</em>

Σ(Dproducts) = 6 × 413 + 1 × 347 = 2825 kJ

<em>For the system</em> :

ΔHrxn = 2700 - 2825 = -125 kJ

4 0
3 years ago
Combining a base and an acid forms
Rainbow [258]

Answer: C. Salt and Water

Explanation:

The reaction between an acid and a base will have salt and water as its end product. This process is known " Neutralization  Reaction".

HCl    +                   NaOH         ----------->            NaCl       +           H2O

Hydrochloric          Sodium                                  Sodium                Water

Acid                     Hydroxide (base)                   Chloride(Salt)                            

4 0
3 years ago
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