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Elodia [21]
3 years ago
8

Elements in Group 4A

Chemistry
1 answer:
steposvetlana [31]3 years ago
6 0

Answer:

helium hydrogen

Explanation:

lithium beryllium bottom carbon

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An electron in a hydrogen atom relaxes to the n=4 level, emitting light of 74 THz.
Solnce55 [7]
Delta E = Ef - Ei
E = energy , h = plank constant  , v = frequency
h= 6.626 * 10 ^-34 j*s  ,  T = 10 ^ 12  , v = 74 * 10 ^12 Hz  ,  Hz = s^-1 

E = ( 6.626 * 10^ -34 j*s) ( 74 * 10 ^ 12 s^ -1 )  =   4.90 * 10 ^ -20 J
Delta E  = Ef  -  Ei
-4.90 * 10 ^ -20 J =  -2.18 * 10 ^ -18J ( 1/4 ^2 - 1/x ^2)
0.0225 = 0.0625 -  ( 1/x ^ 2)
0.225 - 0.0625 =  - 1/ x ^ 2 

- 0.0400 = - 1/x ^2    =   -1 / - 0.0400    =   x^2
25   =  x^2 
     x = 5 




6 0
3 years ago
Which one of the following is a correct representation of an alpha particle?
Alex Ar [27]

Answer:

₂He⁴  

Explanation:

Alpha radiations are emitted as a result of radioactive decay. The atom emit the alpha particles consist of two proton and two neutrons. Which is also called helium nuclei. When atom undergoes the alpha emission the original atom convert into the atom having mass number less than 4  and atomic number less than 2 as compared to parent atom the starting atom.

Properties of alpha radiation:

Alpha radiations can travel in a short distance.

These radiations can not penetrate into the skin or clothes.

These radiations can be harmful for the human if these are inhaled.

These radiations can be stopped by a piece of paper.

₉₂U²³⁸   →   ₉₀Th²³⁴  + ₂He⁴  + energy

6 0
3 years ago
I need help with number 4 I mean k think I'm right
adell [148]
Its b because it explains it better than a waterfall does
5 0
3 years ago
A 29.0-g sample of water at 290. K is mixed with 51.0 g water at 300. K. Calculate the final temperature of the mixture assuming
zubka84 [21]
Let me conduct my research
5 0
2 years ago
Read 2 more answers
Anyone could help me out?
Hoochie [10]

1.4 mg/dL = 0.014 g/L

Explanation:

Milligrams per deciliter to grams per liter

There is 1000 grams of mg/dL of 1 g/L

8 0
3 years ago
Read 2 more answers
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