Helium (He) does not have the same number of valence electrons as other elements in its group.
The periodic table is divided into groups with the last number of the group coinciding with the number of electrons that an element in the group has in its outermost or valence shell.
Helium is in group 18 which means that it should have the same number of valence electrons as :
- Neon
- Argon
- Krypton
- Xenon and,
- Radon
Yet Helium only has 2 valence electrons. We can therefore conclusively say that Helium does not have the same number of valence electrons as other elements in its group.
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The magnitude of gravity is expressed in terms of its acceleration. So the magnitude of ' g ' at that altitude is exactly 6.5 m/s^2.
Answer:

Explanation:
The formula for kinetic energy is:

We can plug in the given values into the equation:



Answer:
The correct answer is "0.32 mL".
Explanation:
The given values are:
Density of gold bar,
d = 19.3 g/mL
Mass of gold bar,
m = 6.3 grams
Now,
The volume will be:
⇒ 
or,
⇒ 
On substituting the values, we get
⇒ 
⇒ 
Given: Heat Qout means useful work = 2800 J
Heat Qin = 8900 J
Required; Efficiency = ?
Formula: Efficiency = Qout/Qin = x 100%
= 2800 J/8900 J = 0.3146 X 100 %
Efficiency = 31.46%