Answer:
Helium
Explanation:
Helium is the least reactive element, since it is a noble gas with the smallest amount of valence rings.
Answer:
Scientists have studied eclipses since ancient times. Aristotle observed that the Earth's shadow has a circular shape as it moves across the moon. He posited that this must mean the Earth was round. Another Greek astronomer named Aristarchus used a lunar eclipse to estimate the distance of the Moon and Sun from Earth
Answer:
Explanation:
Time taken to complete one revolution is called time period.
So, Time period, T = 1 s
Diameter = 1.6 mm
radius, r = 0.8 mm
Let the angular speed is ω.
The relation between angular velocity and the time period is

ω = 2 x 3.14 = 6.28 rad/s
The relation between the linear velocity and the angular velocity is
v = r x ω
v = 0.8 x 10^-3 x 6.28
v = 0.005 m/s
1. What does PE stand for? Physical Education
2. Name one common PE exercise? Your choice A knee push up B piano keys