Answer:
pH = 4.25
Explanation:
A solution composed of a weak acid and its conjugate base is a <em>buffer solution</em>. To calculate the pH of a buffer solution we use the Henderson-Hasselbach equation:
pH = pKa + log ([conjugate base]/[weak acid]
In this case, we have the following data:
[conjugate base] = [sodium benzoate] = 0.230 M
[weak acid] = [benzoic acid] = 0.205 M
The pKa of benzoic acid is 4.2. So, we introduce the data in the equation:
pH = 4.2 + log (0.230 M/0.205 M) = 4.2 + 0.050 = 4.25
Answer:
Here's what I get
Explanation:
A. Initial observation
Gary's shell had slime and an odour.
B. Independent variable
The independent variable is the one that the experimenter changes.
There are two independent variables: the rubbing with seaweed and the drinking of Dr. Kelp.
C. The dependent variable
The dependent variable is the amount of slime and odour.
D. The conclusion
Sponge Bob can conclude that rubbing the shell with seaweed and drinking Dr. Kelp removes the slime and odour.
However, this was a poorly designed experiment. He doesn't know if it is the seaweed or the Dr. Kelp that gives the result or if he must use both together. He should change only one independent variable at a time.
Answer:
56°
Explanation:
First calculate 

The interplanar spacing can be calculated from:

The diffraction angle is determined from:

Solve for 

The diffraction angle is:

Answer: (C) Statements (i) and (iii)
Explanation: According to byjus.com, group VII elements are known as Halogens.
Not only that, but bbc.co.uk says " Atoms of group 7 elements all have seven electrons in their outer shell. This means that the halogens all have similar chemical reactions ."
It may just be (b) though as these are chemical reactions.