Answer:
In addition to observing wind speed, wind direction, temperature, air pressure, and humidity, meteorologists observe <em>WEATHER</em><em>.</em><em> </em>
<em>HOPE</em><em> </em><em>IT</em><em> </em><em>HELPS</em><em>!</em><em> </em>
It means <span>a substance formed by chemical union of 2 or more elements or ingredients in definite proportion by weight.</span>
A control sample serves as a sample used to eliminate errors or minimize them. Also, it is used to prevent the effect of one parameter which is not the subject being studied. For instance, in an adsorption experiment a control sample is always included wherein in a flask it only contains the adsorbate solution. The said sample is responsible for calculating how much of the adsorbate is being adsorbed on the sides of the flask.