The correct answer is option C, that is, hypothesis.
The hypothesis is the starting building block in the scientific method. It is also illustrated as an educated guess, based on previous observation and knowledge. A hypothesis refers to a recommended solution for an unexplained event, which does not fit into the present accepted scientific theory.
The fundamental concept of a hypothesis is that there is no pre-determined result. For a hypothesis to be considered as scientific hypothesis, it has to be something, which can be refuted or supported via carefully crafted observation or experimentation.
Answer:
4Ba(CO3) -> 4BaO2 + 2CO2
Explanation:
I looked at the oxygens to balance this. Ba(CO3) normally has 3 oxygens. BaO2 and CO2 have 4 oxygens total. The common multiple of 3 & 4 is 12. So there should be 12 oxygens on both sides. Then I just found the coefficients that would give 12 oxygens on both sides and can balance the rest of the atoms.
Answer:
(iii) A has pH greater than 7 and B has pH less than 7
Explanation:
Phenolphthalein is a common indicator in acid base titrations. It turns pink in basic conditions and turns colorless in acidic conditions. Thus on addition of solution A it becomes pink so A should be basic having pH more than 7. On addition of B , it turn out to be colorless means that B is an acidic solution having pH less than 7.
Explanation:
White precipitate of silver chloride get dissolves in excess ammonia to formation of complex between silver ions, chloride ions and ammonia molecules.
The chemical reaction is given as:
![AgCl(s)+2NH_3(aq)\rightarrow Ag[(NH_3)_2]^+Cl^-(aq)](https://tex.z-dn.net/?f=AgCl%28s%29%2B2NH_3%28aq%29%5Crightarrow%20Ag%5B%28NH_3%29_2%5D%5E%2BCl%5E-%28aq%29)
When 1 mole of silver chloride is added to 2 mole of an aqueous ammonia it form coordination complex of diaaminesilver(I) chloride.
Molality of the solution is defined as the number of moles of a substance dissolved divided by the mass of the solvent:
Molality = number of moles / solvent mass
From the concentration of 39% (by mass) of HCl in water, we construct the following reasoning:
in 100 g solution we have 39 g hydrochloric acid (HCl)
number of moles = mass / molecular weight
number of moles of HCl = 39 / 36.5 = 1.07 moles
solvent (water) mass = solution mass - hydrochloric acid mass
solvent (water) mass = 100 - 39 = 61 g
Now we can determine the molality:
molality = 1.07 moles / 61 g = 0.018
