The element symbol for oxygen<span> is O and its atomic number is 8. The mass numbers for oxygen must be 8 + 8 = 16; 8 + 9 = 17; 8 + 10 = 18</span>
Answer:
b) warming up a) wavelength a) blank c) sample
Explanation:
<em>To run a spectrophotometry experiment, begin by </em><em>warming up</em><em> the spectrophotometer and preparing the samples.</em> It is important that the equipment is warmed up for at least 30 minutes before starting the measurements.
<em>Be sure to select the correct </em><em>wavelength</em><em>, then run a measurement on the </em><em>blank</em><em> solution.</em> The selected wavelength depends on the analyte of interest. The black solution contains the same matrix but it doesn´t contain the analyte.
<em>Follow up by running measurements on </em><em>sample</em><em> solutions. Once data is collected, turn off the instrument, clean the area, and discard the samples. </em>The samples are those of unknown concentration that we want to determine.
<span>each of two or more forms of the same element that contain equal numbers of protons but different numbers of neutrons in their nuclei, and hence differ in relative atomic mass but not in chemical properties.</span>
Answer:
+ => +
Explanation:
Nitric acid reacts with sodium carbonate to form sodium nitrate, carbon dioxide and water.
Sodium carbonate + nitric acid => sodium nitrate + water + carbon dioxide
2HNO3 + Na2O3 => 2NaNO3 + CO2 + H2O
So the net ionic equation is as follows:
+ => +
The sodium ion and the nitrate ions are not involved in the net equation because they are not changed in the reaction.