Buffers - mixtures of conjugate acid and conjugate base at ±1 pH unit from pH = pKa. Resistant to changes in pH in response to small additions of H+ or OH-. ... Polyprotic acids - dissociation of each H+ can be treated separately if the pKa values are different
A locating agent is needed in an experiment to separate amino acids by chromatography as it helps to analyze colorless substances on paper.
<h3>What is chromatography?</h3>
Chromatography is an analytical method frequently used to separate a chemical mixture into its components, allowing for in-depth analysis of each component.
There are many different types of chromatography including liquid, gas, ion-exchange, and affinity chromatography, but they all use the same basic principle.
<h3>What is the use of a locating agent in Chromatography?</h3>
In paper chromatography, colorless compounds are examined using a locating agent.
It is a chemical that combines with colorless substances to produce colorful compounds that are easy to see for analysis. Ninhydrin spray is an example of a locating agent of this type.
Thus, a locating agent is used in an experiment to separate amino acids by chromatography as it helps in determining colorless substances on paper.
Learn more about chromatography:
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C unbalanced force is occuring
Answer : (C) Hafnium is the most likely identity of the given substance.
Solution : Given,
Mass of given substance (m) = 46.9 g
Volume of given substance (V) = 3.5 
First, find the Density of given substance.
Formula used :

Now,put all the values in this formula, we get
= 13.4 g/
So, we conclude that the density of given substance (13.4 g/
) is approximately equal to the density of Mercury and Hafnium (13.53 and 13.31 g/
respectively).
According to the question the substance is solid at room temperature but Mercury is liquid at room temperature. So, Mercury is not identical to the given substance.
Another element i.e, Hafnium is the element whose density is approximately equal to the given substance and also solid at room temperature. And we know that the melting point of solid is high.
So, Hafnium is the most likely element which is the identity of the given substance.
The equation that relates both energy and wavelength is:

where e is the energy and lambda is the wavelength.
Therefore, as we can see from this equation, the energy of an electromagnetic wave is inversely related to the wavelength of the electromagnetic wave.