The correct answer is I disagree. Elements form all pure substances, but some pure substances include elements bonded together to form molecules and compounds.
Elements are pure substances but these elements also make other things such as water. The water molecule is made of two elements called oxygen and Hydrogen. Now water itself is a pure substance as it is chemically bonded hydrogen and Oxygen but it is composed of more than one element
Answer: h = 3R
Explanation:
Using the law of conservation of energy,
Total energy at the beginning of the launch would be equal to total energy at any point.
kinetic energy + gravitational potential energy = constant
Initial energy of the projectile =
... (1)
where R is the radius of the Earth, M is the mass ofthe Earth, m is the mass of the projectile.
escape velocity, 
Total energy at height h above the Earth where speed of the projectile is half the escape velocity:
...(2)
(1)=(2)
⇒
⇒
⇒
⇒
⇒h = 3R
Thus, at height equal to thrice radius of Earth, the speed of the projectile would reduce to half of escape velocity.
the answer is true acceleration is the change in distance over time.
hope this helps
The amounts are the independent boiling water is dependent