X ml - <span>25% alcohol mixture
y ml - </span><span>90% alcohol mixture
x+y = 455
0.25x ml alcohol in </span>x ml of 25% alcohol mixture
0.9y ml alcohol in y ml of 90% alcohol mixture
0.75*455= 341.25 ml alcohol in 455 ml of 75% alcohol mixture
0.25x+0.9y=341.25
System of equations:
x+y = 455 /*(-0.25) ------> -0.25x-0.25y = -0.25*455
0.25x+0.9y=341.25
-0.25x-0.25y=-113.75
0.25x+0.9y=341.25 Add both equations
0.25x+0.9y-0.25x-0.25y=341.25-113.75
0.65y =227.5
y=227.5/0.65 = 350 ml of 90% alcohol mixture
x+y=455
x+355=455
x=100 ml of 25% alcohol mixture
Answer:
The correct answer to this question is (c) 25.0 m
Explanation:
To solve this we list out the variables thus
mole fraction of sodium hydroxide = 0.310
Mole fraction = number of moles of a component ÷ total number of moles in the solution
Mole fraction = 0.310
In a saturaturated aqueous solution we have NaOH and water
∴ Number of moles of water molecules per unit = 1 - 0.310 = 0.690
However 0.690 moles of H₂O weighs = 0.690 mole × 18.01528 g/mol =12.43 g = 0.01243 kg of H₂O
But the molality = number of moles per Kilogram of H₂O
therefore molality of NaOH in the sample of solution =
(0.310 mol of NaOH )÷(0.01243 kg of H₂O)
= 24.93 mol/kg or ≅ 25.0 m
The postulate of Dalton's atomic theory that atom is indivisible particle and can be subdivided into smaller particles was later changed because atom can be divided into neutrons, protons and electrons. It was changed because after later finding out that the atom can be divided, the theory was changed to the correct finalized theory.
Hope this helps!!!
Answer:
Because the student made use of scientific instruments in one case and his senses in the other.
Explanation:
Scientific experiments involve making observations, which is key to the outcome of any experiment. According to the scientific method, collecting of data is one of the steps in fulfilling the scientific procedure. One way to collect data is by using scientific instruments to measure, which is then recorded. This is the case for the WEIGHT of the sugar the student recorded.
Another way to collect data is by making use of the senses e.g eyes, nose, skin etc. to observe and record the perceived information. Therefore, the pieces of information collected by the student represent DATA because he made use of his senses and scientific instruments.
Sedimentary rock can be minazute by adding more heat n pressure
