Answer:
That unknown substance is water
Explanation:
Answer:
See Explanation
Explanation:
An endothermic reaction is one in which energy is absorbed and the change in enthalpy for the reaction is positive.
If we look at the reaction 2HgO + 45kcal ----> 2Hg + O2; we will notice that
i) 45kcal of energy was taken in (absorbed) for the reaction to occur
ii) The value of the reaction enthalpy is positive
For these two reasons, the reaction is an endothermic reaction as written.
C is the answer.
It says on the third picture that Bohr refined Rutherford's model by giving distinct orbits for the electrons with distinct radii.
The answer is 2 electrons.
The electron configuration of calcium is 2:8:8:2
Calcium has two electrons in its outermost shell. These are its valence electrons and are the ones used in bonding with other elements. Valence electrons of an atom are those electrons that are in its outer energy shell or that are available for bonding.
Calcium is a metal. When metals react with non-metals, electrons are transferred from the metal atoms to the non-metal atoms forming ions. The resulting compound is known as an ionic compound.
For example, when calcium metal reacts with chlorine gas, calcium gives up its two valence electrons and Chlorine accepts them resulting in a new substance called calcium chloride in which the two elements have ended up forming ionic bonds.
Invasive species can do all sorts of damage to an existing ecosystem, including changing habitats and starving native animals of food and resources.
<h3>What is an invasive species?</h3>
An invasive species is an organism that causes ecological or economic harm in a new environment where it is not native.
Invasive species can change the food web in an ecosystem by destroying or replacing native food sources. The invasive species may provide little to no food value for wildlife. Invasive species can also alter the abundance or diversity of species that are important habitats for native wildlife.
Learn more about the invasive species here:
brainly.com/question/21452505
#SPJ1
