Answer:
- <u>21.4 ml (second choice)</u>
Explanation:
<u>1) Data:</u>
a) C₁ = 60.0% (initial solution)
b) V₁ = 30.0 ml (initial solution)
c) C₂ = 0% (pure water)
d) V₂ = ? (pure water)
e) C₃ = 35.0% (final concentration)
<u>2) Formula:</u>
- C₁V₁ + C₂V₂ = C₃V₃
- V₁ + V₂ = V₃ (assuming volume addtivity)
<u>3) Solution:</u>
<u />
a) Substitute values in the first formula:
- 60.0% × 30 ml + 0 = 35% (30 ml + V₂)
b) Solve the equation (units are supressed just to manipulate the terms)
- V₂ = 7.5 / 0.35 = 21.4 ml ← answer
Answer:
Taking reading of the volume level of liquid in a buret while it is inclined leading to parallax error
Explanation:
Practices that will not help you make accurate volume reading on a buret are
1. Leaving air bubbles buret tip or in the stopcock
2. Error due to parallax: Taking volume reading while looking at the scale of an inclined buret. Looking down the buret gives it an appearance of a higher reading than actual reading while up towards the meniscus will make it look lower than the actual value
3. Pouring in the liquid too rapidly into the buret forming droplets on the inner walls of the buret which can alter the volume reading of the buret when the drops settle into the remaining liquid in the buret
The correct question is: How many moles are in 
atoms of boron.
Answer: There are 145 moles present in atoms of boron.
Explanation:
According to the mole concept, there are 
atoms present in one mole of every substance.
Hence, number of moles present in atoms is calculated as follows.
Thus, we can conclude that there are 145 moles present in atoms of boron.
They have small differences in electronegativity
i think thats right
