Mixing calcium carbonate and HCl.
Heating copper sulfate pentahydrate.
Mixing potassium iodide and lead nitrate.
Combining magnesium and hcl.
Burning the candle.
Let's look at the available options and see what are chemical changes and what are physical changes. As a side note, line breaks, capitalization, and punctuation are VERY important. I spent almost as much time attempting to actually figure out what your options were as I spent in distinguishing between what were chemical reactions and physical changes.
Crushing calcium carbonate.
* This is a mere physical change. You start with large pieces of calcium carbonate and end up with smaller pieces. So this is a bad choice.
Mixing calcium carbonate and HCl.
* This is a chemical reaction where the calcium carbonate and hydrochloric acid react with each other and produce carbon dioxide plus other compounds. So this is a good choice.
Boiling water.
* Another physical change from liquid to vapor. You can cool down the resulting vapor and end up with the original water. So this is a bad choice.
Heating copper sulfate pentahydrate.
* This is a chemical change in that you're converting CuSO4 . 5H2O(s) into CuSO4 and H2O. So this too is a good choice.
Separating iron filing and sulfur.
* You start out with iron filings and sulfur and end up with iron filings and sulfur. Things are a bit more orderly, but no chemical reactions have occurred. So this is a bad choice.
Mixing potassium iodide and lead nitrate. * You start with 2 white solids and upon mixing them, you get a yellow solid.
A chemical reaction has occurred. So this is a good choice.
Combining magnesium and hcl.
* When you combine these two items, you get hydrogen gas as a product. So you have a chemical reaction. And this is a good choice.
Burning the candle.
* Another chemical reaction. The wax combines with the oxygen in the air and produces water vapor and carbon dioxide. So this is a good choice.
Answer:
B. to determine that electric beams in cathode ray tubes were actually made of particles
Explanation:
False because that doesn’t make sense
Answer:
All the option are correct
Explanation:
The ocean currents have been associated with past climatic shifts during critical periods (for example, the ice ages), where modifications in water circulation might have caused important climatic changes.
From a biological point of view, the ocean currents may be associated not only with the climate but also biogeochemical cycles through modifications in the distribution of heat and freshwater. Thus, the changes in ocean circulation may produce biogeographical shifts by affecting the local climate. The importance of ocean currents in affecting biodiversity is also represented by the equilibrium of coral reef ecosystems, where this equilibrium is broken up by factors such as transport of pollutants, temperature conditions, etc., which are known to alter thermosensitive coral species.
Protons and neutrons are made up of tiny particles called quarks.
A proton is a baryon made up two Up and one Down quark.
A neutron is made of two Down quarks and one Up quark.
The Up quarks possess a 2/3 positive charge while the Down quark possess a 1/3 negative charge.
When we refer that a proton consists of two Up quarks and a Down, this simply means that its net appearance matches this description.
It is thought that quarks themselves are surrounded by gluons.
Gluons are the basic particles underlying the strong interaction between protons and neutrons in the nucleus.