Answer:
Yes,
Chemical Reactivity of metals decrease as you go left to right of the periodic table Chemical Reactivity increases as you go down the group....
Explanation:
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Traditionally, gunpowder used in fireworks was made of 75 percent potassium nitrate also called saltpeter mixed with 15 percent charcoal and 10 percent sulfur; modern fireworks sometimes use other mixtures (such as sulfurless powder with extra potassium nitrate) or other chemicals instead
Answer:
V = 1.35 m/s
Explanation:
Given that,
Mass of a railroad car, m₁ = 25,000 kg
Initial speed of a railroad car, u₁ = 4.5 m/s
Initial speed of railroad car that is full of coal, u₂ = 0 (at rest)
We need to find the final velocity of the two railroad cars if they move as one after the collision. It is a case of inelastic collision in which the momentum remains conserved. Using the conservation of linear momentum as follows :
V is the final speed and u₂ = 0
So, the final velocity of the two railroad cars is 1.35 m/s.
Answer:
Explanation:
A physical change is one where only physical, not chemical, properties change. Let's analyze each answer choice.
A. Change in odor
- A change in order is one of the signs of a chemical change.
B. Chopping
- Chopping is a physical change, because no new substances are produced. However, it's not reversible. It's impossible to put something chopped back together again permanently.
C. Phase change
- A phase change is another physical change, plus it is reversible. For example, you can freeze water into ice and melt it back to water.
D. Rusting
- Rusting is a chemical change, because new substances are created.
So, the best answer choice for a reversible physical change is <u>C. phase change</u>.