Answer:
a reference book about weather
Explanation:
Sled going down is in motion
Sled hitting rock is unbalanced
He flew because the of the sudden stop threw them off
Answer:
When observing how thallium reacts with the air of the earth's atmosphere, its hardness or resistance resembled sodium, it was not investigated further to classify it correctly
Explanation:
Now it is known that they contain different numbers of valence electrons and that thallium is a heavy metal like lead and that they have similar characteristics except for their melting point where thallium is higher.