<span>a space or vesicle within the cytoplasm of a cell, enclosed by a membrane and typically containing fluid.</span>
A compound was found to be soluble in water. It was also found that addition of acid to an aqueous solution of this compound resulted in the formation of carbon dioxide. Which one of the following cations would form a precipitate when added to an aqueous solution of this compound?
Options
a. NH4
b. K
c. Cr
d. Rb
e. Na
Answer: c: Cr
Explanation:
The aforementioned reaction are banters for to distract ones focus from the question.
However it should be noted that
Cr can be found in tannery waste water showing that it can be soluble in water.
The carbonate compound when reacting with acid CO_2 evolves.
Focusing on the cation that would form a precipitate when added to an aqueous solution.
Chemical precipitation method is a common method for to remove chromium and to recover it from tannery wastewater.
Cr would form a precipitate.
The people use Earth's motion to determine units of time because of its uniform motion which is consistent.
<u>Explanation:</u>
In earlier days, people used to observe the motion of Earth to measure time. This is because, the Earth is moving at constant speed and at constant acceleration. So the change in position of the sun or stars can be easily correlated to the time.
Due to the consistency in the Earth's motion and the accurate repetition of the time period along with the seasons, the Earth's motion can be considered as a responsible source to determine the units of time.
The chemical formula for calcium hydroxide is Ca(OH)₂ and that of nitric acid is HNO₃. By these chemical formula it can be deduced that the number of equivalents per mole of Ca(OH)₂ is 2 because of 2 OH⁻ and for HNO₃ is 1 because of H⁺.
For the neutralization reaction, the number of equivalents should be equal.
V₁n₁ = V₂n₂
Substituting the known values and with the incorporation of the concept above,
(V₁)(0.0250 mol/L)(2 equivalents/mol) = (33.50 mL)(0.020 mol/L)(1 equivalent/mol)
V₁ = 13.4 mL
Hence, the volume of calcium hydroxide needed is approximately equal to 13.4 mL.
Answer: -
Substance A is carbon dioxide and Substance B is oxygen.
Explanation: -
Photosynthesis reaction involves the process of conversion of light energy of the sun into chemical energy by the green chlorophyll found in plants leaves.
The chemical equation for the process is
6 CO₂ +6 H₂O → C₆H₁₂O₆ + 6O₂
As we can see Carbon dioxide CO₂ reacts with water H₂O to form glucose. Oxygen is the gaseous product formed.
Thus Substance A is carbon dioxide and Substance B is oxygen.
