Answer:
A. Obsidian
Explanation:
It fits the property described in the question.
It cools so fast that no visible crystal or grain could form. It has high silica Composition, black and glassy. It is also used to make tools with sharp edges
Answer:
The true statement is that different gases with the same mass and temperature always have the same average kinetic energy. This is one of the postulates of the kinetic theory of matter.
If we two objects A and B, they will have mass mA and mB and velocity vA and vB respectively. If K.E = 1/2mv^2 . Then it follows that
1/2mAvA = 1/2mBvB. Since the mass is the same it means the velocity of the two objects should be the same so that they have the same average kinetic energy.
The fact that volcanic rock has often been found early in the rock record but less frequently in later rock layers suggest to scientists the following conclusion about early earth: <span>volcanic activity was more common in the past than it is today.
</span>Besides volcanic activity in general, also huge volcanic eruptions<span> were much </span>more common than today<span>.</span>
