Answer:
Explanation:
We know that , the reaction between NaOH and HCl is given as
Form the above reaction we can say that
Number of moles of HCl =Number of moles of NaOH
Therefore
Therefore the numbers of moles needed of HCl wil be 
The branch of science that deals with the identification of the substances of which matter is composed
you can learn by reading about it or google it
The answer is D) There are effective collisions between the particle[s]. Collisions between particles is what happens during a chemical reaction (in this case, the oxygen and iron particles collide).
Choice A (the particles are heated) is incorrect because heating particles will make the reaction faster. However, there must be a reaction there in the first place.
Choice B (the atmospheric pressure decreases) is incorrect because decreasing pressure will increase volume, which does not have anything to do with the speed of the reaction. Assuming you have learned about equilibrium in a chemical system/equation, you will know that changing the pressure will make the equation shift to the side with less moles of elements. However, the number of moles is not specified.
Choice C (there is a catalyst present) is incorrect because a catalyst is something that speeds up a reaction. Similarly to choice A, there is no reaction to begin with.
Hope this helps. :)
Answer:
Explanation:The main problem with Bohr's model is that it works very well for atoms with only one electron, like H or He+, but not at all for multi-electron atoms.
2,500 years ago, Democritus suggested that all matter in the universe was made up of tiny, indivisible, solid objects he called "atomos." However, other Greek philosophers disliked Democritus' "atomos" theory because they felt it was illogical.
