(1.9 yr) x (365.24 day/yr) x (86,400 sec/day) x (10⁹ nsec/sec)
= (1.9 x 365.24 x 86,400 x 10⁹) nanosec
= 6.00 x 10¹⁶ nanoseconds
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 correct answer (sample response) is:
The image seems to be behind the mirror, but nothing is really there.
Include the following in your response:
The image appears to be behind the mirror.
If someone looks behind the mirror, there is no image there.

True, because it is the state between solid and liquid
Answer:
a) 19440 km/h²
b) 10 sec
Explanation:
v₀ = initial velocity of the car = 45 km/h
v = final velocity achieved by the car = 99 km/h
d = distance traveled by the car while accelerating = 0.2 km
a = acceleration of the car
Using the kinematics equation
v² = v₀² + 2 a d
99² = 45² + 2 a (0.2)
a = 19440 km/h²
b)
t = time required to reach the final velocity
Using the kinematics equation
v = v₀ + a t
99 = 45 + (19440) t
t = 0.00278 h
t = 0.00278 x 3600 sec
t = 10 sec