Answer:
Obsidian is not a mineral as the atoms or molecules in obsidian do not have a crystalline structure.
Explanation:
Obsidian originates naturally and is formed by igneous rock.
When felsic larva comes out from the volcano,it rapidly cools down and thus form obsidian.It is pure black in color but some times color differ due to presence of some impurities.
It is brittle,but hard.It is not a mineral and is called as mineraloids and is not found in crystalline form,.
The main constituent is SiO2.
It is found in the margin of rhyolitic lava.
Answer:

Explanation:
<u>The alkaline solution: </u>
40 ml of 0.1 M KOH

<u>The acid solution: </u>
30 ml of 0.1 M HCl

The neutralization reaction:

For 1 mol of HCl, 1 mol of KOH is consumed. If 0.003 mol of HCl are added, 0.003 mol of KOH reacted.
After titration:


Concentration (don't forget to add the volumes)

Calcualtion of the pOH:
![pOH=-log([OH^-])=-log(0.0143)=1.84](https://tex.z-dn.net/?f=pOH%3D-log%28%5BOH%5E-%5D%29%3D-log%280.0143%29%3D1.84)
For the pH:

The kind of gases probably in astronaut suit is nitrous oxide