Answer:
3 element i.e carbon (C), hydrogen (H) and oxygen.
Explanation:
The following data were obtained from the question:
Subtance >>>>>>>> Chemical Formula
Glucose >>>>>>>>> C₆H₁₂O₆
Methane >>>>>>>> CH₄
Ethanol >>>>>>>>> C₂H₅OH
Hydrogen peroxide >> H₂O₂
From the above table, we can see that ethanol (C₂H₅OH) contains carbon (C), hydrogen (H) and oxygen
Therefore, the total number of elements present in ethanol, C₂H₅OH is 3.
Se2- has 34 protons and 36 electrons so it gets a 2- charge.
1.
- The changing of liquid to a gas.
2.
- The major source of pollution.
3.
- Carbon dioxide and water vapor trapping heat given off by Earth.
4.
- Layer absorbing ultraviolet rays.
5.
- The changing of a gas to a liquid.
6.
- Layer responsible for reflecting radio waves.
7.
- The layer in which weather changes.

Structure is in document below.
The mononitration of p-xylene can be easily carried out at 30 degrees C.
Para-xylene<span> (</span><span>p-xylene</span><span>) is an </span>aromatic hydrocarbon, <span>one of the three </span>isomers<span> of </span>dimethylbenzene. Para-xylene is colorless and highly flammable, not acutely toxic and has some <span>narcotic effects.</span>