Answer:
The correct answer is Hollow Sphere.
Answer:
pKa = 3.51
Explanation:
The titration of acid solution with NaOH can be illustrated as:
Given that:
Volume of acid solution 
Volume of NaOH 
Molarity of acid solution 
Molarity of NaOH 
For Neutralization reaction:
Making 
the subject of the formula; we have:
However; since the number of moles of NaA formed is equal to the number of moles of NaOH used : Then :
Total Volume after titration = ( 25 + 18.8 ) m
= 43.8 mL
Molarity of salt (NaA ) solution = 
= 
= 0.0429 M
After mixing the two solution ; the volume of half neutralize solution is = 25 mL + 43.8 mL
= 68.8 mL
Molarity of NaA before mixing 
Volume 
Molarity of NaA after mixing 
Volume 
∴
Molarity of acid before mixing = 0.0725 M
Volume = 25 mL
Molarity of acid after mixing = 
= 0.0273 M
Since this is a buffer solution ; then using Henderson Hasselbalch Equation
![pH = pKa + log \frac{[salt]}{[acid]}](https://tex.z-dn.net/?f=pH%20%3D%20pKa%20%2B%20log%20%5Cfrac%7B%5Bsalt%5D%7D%7B%5Bacid%5D%7D)
![3.51= pKa + log \frac{[0.0273]}{[0.0273]} \\ \\ 3.51= pKa + log \ 1 \\ \\ 3.51= pKa + 0 \\ \\ pKa = 3.51](https://tex.z-dn.net/?f=3.51%3D%20pKa%20%2B%20log%20%5Cfrac%7B%5B0.0273%5D%7D%7B%5B0.0273%5D%7D%20%5C%5C%20%20%5C%5C%203.51%3D%20pKa%20%2B%20log%20%5C%201%20%20%5C%5C%20%5C%5C%203.51%3D%20pKa%20%2B%200%20%5C%5C%20%5C%5C%20pKa%20%3D%203.51)
Answer:
23.61m/s
Explanation:
Km/hr is a unit of expressing the speed of a body. Speed is the rate of change of distance with time. Also, the same unit is applicable for expressing the velocity of a body. But to find the velocity, we must emphasize the direction of motion of the body.
Given parameter:
85km/hr to cm/s
Note:
1000m =1km
3600s = 1hr
So;
85 x
Cancelling out km and hr;
= 85 x 0.278m/s
= 23.61m/s
Answer:
(C) Only particular quantized energies are given off by excited electrons in the form of light.
Explanation:
Atomic emission spectra often have gaps that help to create the color lines.
These gaps occur as a result of heat energy absorbed by electrons in the atoms, making them to be excited and allow them to jump into higher energy levels by emitting only particular quantized energies in the form of light.
Therefore, the correct option is "C"
(C) Only particular quantized energies are given off by excited electrons in the form of light.
