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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!

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I need help can someone explain this to me
ELEN [110]
A.) top to bottom:
900, 1000, 1200
B.) top to bottom:
250, 450
3 0
3 years ago
An unknown mass of aluminum requires 6290 joules to raise
Alex Ar [27]

Answer:

124.579 g

Explanation:

Amount of heat required to change the temperature of body is given by the equation given below

Q = m* c * ΔT ____________________equation A

where Q is the total heat energy required by the any object

c is the specific heat capacity of the body J/gK

ΔT is the difference of final temperature of the object and initial temperature of the object

______________________________________

Given Q = 6290 joules

c = 0.900 J/gK

To calculate the temperature in kelvin from Celsius

we can use the formula

K = C + 273

initial temperature  = 23.9°C

initial temperature on kelvin scale =  23.9° + 273 = 296.9

Final temperature  = 80°C

initial temperature on kelvin scale =  80° + 273 = 353

ΔT(temperature difference) = 353 - 296.9 = 56.1

___________________________________________

let the mass of of the  aluminum be m g

substituting the value of Q , c, ΔT in equation A we have

Q = m* c * ΔT

=> 6290 = m * 0.900 * 56.1

=> m = 6290/(0.900 * 56.1 )

=> m = 6290/50.49

=> m = 124.579 g

The mass of the  aluminum is 124.579 g

8 0
3 years ago
What is an ecosystem?<br> living environment by the way
MAVERICK [17]
An ecosystem is a lot of things and places that need each other to survive
4 0
4 years ago
1. How many grams of B are present in 3.35 grams of boron tribromide ?
Andre45 [30]

Answer:

The answer to your question is:

Explanation:

1. How many grams of B are present in 3.35 grams of boron tribromide ?

________ grams B.

MW BBr₃ = 251 g

                            251 g of BBr₃ ----------------------  11 g of B

                             3.35 g          -----------------------    x

                           x = (3.35 x 11) / 251 = 0.147 g of B

2. How many grams of boron tribromide contain 4.69 grams of Br ?

________grams boron tribromide.

MW BBr₃ = 251g

                             251g of BBr₃ -----------------   80 g of Br

                                   x               ----------------- 4.69 g

                           x = (4.69 x 251)/ 80 = 14.71 g of BBr₃

3. How many grams of N are present in 4.11 grams of nitrogen trifluoride ?

________grams N.

MW NF₃ = 71 g

                               71 g of NF₃    -----------------   14 g of N

                               4.11 g              ----------------     x

                               x = (4.11 x 14) / 71 = 0.81 g of N

4. How many grams of nitrogen trifluoride contain 3.07 grams of F ?

________grams nitrogen trifluoride.

MW NF₃ = 71

                                71 g of NF₃ ---------------------   19 g of F

                                  x               ---------------------   3.07 g

                                 x = (3.07 x 71) / 19 = 11.5 g of NF₃

5.How many grams of Co3+ are present in 1.16 grams of cobalt(III) iodide?

________grams Co3+.

MW CoI₃ = 440 g

                             440 g of CoI₃ ------------------  59 g of Co

                              1.16 g             ------------------   x

                              x = (1.16 x 59) / 440 = 0.16 g of Co

6. How many grams of cobalt(III) iodide contain 2.28 grams of Co3+?

________grams cobalt(III) iodide.

MW CoI₃ = 440 g

                             440 g of CoI₃ ------------------  59 g of Co

                               x                   -----------------   2.28 g of Co⁺³

                              x = (2.28 x 440) / 59

                              x = 17 g of CoI₃

5 0
3 years ago
Draw the major organic product for the reaction of 1-phenylpropan-1-one with the provided phosphonium ylide.
prohojiy [21]

Answer:

2-methylene propylbenzene

Explanation:

The Wittig Reaction is a reaction that converts aldehydes and ketones into alkenes through reaction with a phosphorus ylide.

The ketone in this case is 1-phenylpropan-1-one. The provided phosphonium ylide is shown in the image attached. The reaction involves;

i) alkylation  

ii) addition

The product of the major organic product of the reaction is 2-methylene propylbenzene.

4 0
3 years ago
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