1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Vadim26 [7]
3 years ago
5

What is the electron configuration of an element with atomic number 20? A. 1s2 2s2 2p6 3s2 3p5 B. 1s2 2s2 2p6 3s2 3p6 C. 1s2 2s2

2p6 3s2 D. 1s2 2s2 2p6 3s2 3p6 4s2 E. 1s2 2s2 2p6
Chemistry
2 answers:
Cerrena [4.2K]3 years ago
8 0

D.  The number of electrons equals the atomic number for a neutral element.  Each number after the letter refers to the number of electrons in that shell.  So for D, 2+2+6+2+6+2 = 20 electrons, which is equal to the atomic number.

Leni [432]3 years ago
6 0

D. 1s2 2s2 2p6 3s2 3p6 4s2

Hope this helps!

<u />

You might be interested in
The time required for one-half of the atoms from a sample of a radioactive substance to decay is called its _____.
Orlov [11]
A.) half - life of a radioactive substance is defined as the time during which concentration of the substance becomes half the initial value.
8 0
3 years ago
Read 2 more answers
what would you be most likely to measure by immsering and object in water and seeing how much the water level rises
Katena32 [7]
Mass, if you know what element you are working with.
4 0
3 years ago
A chemist must prepare of 800.0 ml potassium hydroxide solution with a pH of 13.00 at 25°.
ArbitrLikvidat [17]

Answer:

4.48 grams is the mass of potassium hydroxide that the chemist must weigh out in the second step.

Explanation:

The pH of the solution = 13.00

pH + pOH = 14

pOH = 14 - pH = 14 - 13.00 = 1.00

pOH=-\log[OH^-]

1.00=-\log[OH^-]

[OH^-]=10^{-1.00} M=0.100 M

KOH(aq)\rightarrow K^+(aq)+OH^-(aq)

[KOH]=[OH^-]=[K^+]=0.100 M

Molariy of the KOH = 0.100 M

Volume of the KOH solution = 800 mL= 0.800 L

1 mL = 0.001 L

Moles of KOH = n

Molarity=\frac{Moles}{Volume(L)}

0.100 M=\frac{n}{0.800 L}

n = 0.0800 mol

Mass of 0.0800 moles of KOH :

0.0800 mol × 56 g/mol = 4.48 g

4.48 grams is the mass of potassium hydroxide that the chemist must weigh out in the second step.

4 0
3 years ago
What are the safety procedures for nuclear accidents nowadays?
Zigmanuir [339]

Explanation:

Take shelter in a hard wall building

Close doors and windows cut off ventilation

4 0
3 years ago
S8 + 24 F2 ⟶ 8 SF6
Arturiano [62]

Answer:

Theoretical Yield of SF₆ = 2.01 moles

Explanation: If you understand and can apply the methodology below, you will find it applies to ALL chemical reaction stoichiometry problems based on the balanced standard equation; i.e., balanced to smallest whole number coefficients.

Solution 1:

Rule => Convert given mass values to moles, solve problem using coefficient ratios. Finish by converting moles to the objective dimensions.

Given      S₈            +          24F₂            =>    8SF₆

             425g                    229g                      ?

= 425g/256g/mol.      = 226g/38g/mol.

= 1.66 moles S₈          = 6.03 moles F₂ <= Limiting Reactant

<em>Determining Limiting Reactant => Divide moles each reactant by their respective coefficient; the smaller value will always be the limiting reactant. </em>

S₈ = 1.66/1 = 1.66

F₂ = 6.03/24 = 0.25 => F₂ is the limiting reactant

<em>Determining Theoretical Yield:</em>

Note: When working problem do not use the division ratio results for determining limiting reactant. Use the moles F₂ calculated from 229 grams F₂ => 6.03 moles F₂. The division procedure to define the smaller value and limiting reactant is just a quick way to find which reactant controls the extent of reaction.  

Given      S₈            +          24F₂            =>    8SF₆

             425g                    229g                      ?

   = 425g/256g/mol. = 226g/38g/mol.

= 1.66 moles S₈          = 6.03 moles F₂ <= Limiting Reactant

<em>Max #moles SF₆ produced from 6.03 moles F₂ and an excess S₈ </em>

Since coefficient values represent moles, the reaction ratio for the above reaction is 24 moles F₂ to 8 moles SF₆. Such implies that the moles of SF₆ (theoretical) calculated from 6.03 moles of F₂ must be a number less than the 6.03 moles F₂ given. This can be calculated by using a ratio of equation coefficients between 24F₂ and 8SF₆  to make the outcome smaller than 6.03. That is,

moles SF₆ = 8/24 x 6.03 moles = 2.01 moles SF₆ (=> theoretical yield)  

S₈ + 24F₂ => 8SF₆

moles SF₆ = 8/24(6.03) moles = 2.01 moles

You would NOT want to use 24/8(6.03) = 18.1 moles which is a value >> 6.03.        

This analysis works for all reaction stoichiometry problems.

Convert to moles => divide by coefficients for LR => solve by mole mole ratios from balanced reaction and moles of given.    

____________________

Here's another example just for grins ...

             C₂H₆O   +   3O₂     =>     2CO₂    + 3H₂O

Given:    253g          307g               ?               ?

a. Determine Limiting Reactant

b. Determine mass in grams of CO₂ & H₂O produced        

Limiting Reactant

moles  C₂H₆O = 253g/46g/mol = 5.5 moles  => 5.5/1 = 5.5

moles  O₂ = 307g/32g/mol = 9.6 moles         =><em>  9.6/24 = 0.4 ∴ O₂ is L.R.</em>

But the problem is worked using the mole values; NOT the number results used to ID the limiting reactant.  

 C₂H₆O   +       3O₂          =>     2CO₂    + 3H₂O

------------ 9.6 mole (L.R.)              ?               ?

mole yield CO₂ = 2/3(9.6)mole = 6.4 mole  (CO₂ coefficient < O₂ coefficient)

mole yield H₂O = 9.6mole  = 9.6mole (coefficients O₂ & CO₂ are same.)

mole used C₂H₆O = 1/3(9.6)mole = 3.2 mole (coefficient  C₂H₆O < coefficient O₂)

For grams => moles x formula weight (g/mole)

7 0
3 years ago
Other questions:
  • If a solution process is exothermic, how does the energy required for dissolving the solute compare with the energy released?
    5·1 answer
  • Above the critical pressure, a substance is a(n) _____ fluid.
    12·1 answer
  • If 1 bus = 12 cars, 3 cars = 1 truck, and 1000 basketballs = 1 truck, how many basketballs can be carried by 8 buses?
    14·1 answer
  • Water is initially present in a state where its molecules are far apart. During a change of state, its molecules slow down. Whic
    7·2 answers
  • Consider the following balanced equation: 5O2(g) + C3H8(g) → 3CO2(g) + 4H2O(l) If 24.9 moles of O2(g) and 6.85 moles of C3H8(g)
    5·1 answer
  • Predict the sign of ΔSsys for each process. Which are positive? A. A pond freezes in winter. B. Atmospheric CO2 dissolves in the
    14·1 answer
  • Which explains the basis of the biuret test?
    15·1 answer
  • Have you ever seen ash fly upward from a campfire? Use at least 2 sentences to explain what you think is happening to the ash to
    8·2 answers
  • The molecular mass of air, at standard pressure and temperature, is approximately 28.97 g/mol. Calculate the mass of 3.33 moles
    10·1 answer
  • How many nitrate ions are in 2 mol of iron (II) nitrate
    13·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!