Answer:
D. 1.2 cm
Explanation:
1st, determine the units. We see that our ruler is in cm.
This rules out A and C.
2nd, determine answer.
We see that the penny extends past 1 and ends at 0.2.
So, the total is 1.2 cm.
This element is found in group 3A, period 3
<h3>Further explanation
</h3>
The maximum number of electrons that can be filled in the nth electron shell is 2n²(n=shell)
-
K shell (n = 1) maximum 2 x 1² = 2 electrons
- L shell (n = 2) maximum 2 x 2² = 8 electrons
- M shell (n = 3) maximum 2 x 3² = 18 electrons
- N shell (n = 4) maximum 2 x 4² = 32 electrons
Electron configuration of element X : 2.8.3 , so :
K shell = 2 ⇒1s²
L shell = 8⇒2s²2p⁶
M shell = 3⇒ 3s²3p¹
Block p: group 13-18 (has a 2p-6p configuration), also called a representative element because it includes metals, non-metals and metalloids
The outer shell 3s²3p¹ : located in group 3A and period 3
group⇒valence electron ⇒3
period⇒the greatest value of the quantum number n⇒3
Explanation:
Helium exists in three different forms due to the phenomenon of isotopy. Isotopy is the existence of two or more atoms of the same element having the same atomic number but different mass numbers due to the differences in the number of neutrons in their nuclei.
- The atoms of these elements are called isotopes.
- This is why Helium can exist in three different forms.
- Isotopes have the same electronic configuration but with the same chemical properties.
Learn more:
isotopes brainly.com/question/1915462
Isotopy brainly.com/question/2593342
#learnwithBrainly
Answer:
You would divide the mass by the density. The volume would be 7 cm^3.
