Answer:
A. When a piece of copper is heated, it combines with oxygen to form copper oxide. The chemical reaction for the same is as follows:
2 Cu (s) + O2(g) => 2CuO
B. The mass of the piece of copper will remain same and there will be no change in its mass. However, its volume will increase, so its density will decrease.
C. This is so because heating copper in its elemental form is a physical change and there is no change in mass during a physical change. Hence, the mass of copper remain same.
Answer:
Option D is good to go!
Explanation: as per the reactivity series more reactive substances will react with the counterpart substance.The most reactive substance here is calcium while the least reactive is aluminium, the magnesium comes in between.As per their reactivity, these substances will react with oxygen.
Explanation:
Answer:
Although chlorine itself usually does not cause environmental harm, it combines rapidly to form chemicals such as dioxins that pollute water, contaminate fish and transfer to humans and larger animals that eat the fish.
Explanation:
Yes, an explanation/ theory for a phenomena in science is not something that is set in stone. If experiments are done that prove the current explanation is false and this is peer checked, then the explanation can absolutely be proven false.
The answer to this question would be A. Energy is released.
When a chemical bond is a form, the bond will either suck up energy or produce energy. So, to be precise the energy is not always released but also can be absorbed. In this case, the energy released number will be a minus.
Options B and C is definitely wrong since the bond is formed by an electron, it won't affects neutron/proton.
Option D might be true since the product is made of 2 or more atoms then it would seem larger. But the size of the actual atom won't be increased.