<u>standardization of a volumetric solutio</u><u>n used for titration is one of the most important preconditions for reliable and transparent titration results.</u>
Answer:
<h2>D</h2>
Explanation:

<em>According to Universe Today, The answer is D because Radiation from the Sun, which is more popularly known as sunlight, is a mixture of electromagnetic waves ranging from infrared (IR) to ultraviolet rays (UV). It of course includes visible light, which is in between IR and UV in the electromagnetic spectrum.</em>

<em>Hope this helps! <3</em>

良い日をお過ごしください!

Explanation:
Elements need a total of eight electrons to gain stability and look like a noble gas. So, they sometimes need sharing of two, four or even six electrons to complete their octate. So, they form double and triple covalent bonds. One more the reason is the interaction between the p orbitals of the combining atoms. for example A double bond, as in ethene H2C=CH2, arises from one combination of the s orbitals and one combination of the p_y orbitals.