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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Explanation:
The potential energy (Ep) = 4500 J
Ep = m. g. h
=> m = Ep/(g.h)
m = 4500/(10×10)
= 4500/100
= 45
so, the mass = 45 kgs
Answer:
6 m/s
Explanation:
Given that :
mass of the block m = 200.0 g = 200 × 10⁻³ kg
the horizontal spring constant k = 4500.0 N/m
position of the block (distance x) = 4.00 cm = 0.04 m
To determine the speed the block will be traveling when it leaves the spring; we applying the work done on the spring as it is stretched (or compressed) with the kinetic energy.
i.e 





v = 6 m/s
Hence,the speed the block will be traveling when it leaves the spring is 6 m/s
A.cooler and hotter rock rise but do not sink.
B.hotter and cooler rock sink but do not rise.
C.hotter rock rises and cooler rock sinks.
D.cooler rock rises and hotter rock sinks.
hotter rock rises and cooler rock sinks.
Answer: Option C.
<u>Explanation:</u>
The process that happens inside the surface of earth makes the rocks inside the surface to either expand or shrink in size because of the presence of heat inside the surface.
Heat rises and as the warmer rock gets further away from the super heated center of the Earth it begins to cool off and starts to sink back toward the super heated center of the Earth where it is reheated and the whole process starts over again. That is what a convection current is.