Gamma radiation have the most penetrating power. It can penetrate through human body, aluminum and other metals. It can be stopped by lead. Hence, the radioactive waste are stored in lead container for safety purposes. The beta ray has more penetrating power than the alpha but less than gamma. The beta radiations can be stopped by aluminum. The alpha radiations have least penetrating power and it can be stopped by human hands.
According to Kepler's second law of orbital motion, a plane's orbital speed changes , depending on how far it is from the sun. The closer a planet is to the sun, the stronger the sun's gravitational pull on it, and the faster the planet moves. The farther away from the sun, the weaker the sun's gravitational pull and the slower it moves in its orbit.
The orbit of a planet around the sun is not a perfect circle, but an ellipse - a flattened circle.
Answer:
A. 2
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