Questions

In chemical nomenclature, the IUPAC nomenclature of organic chemistry is a systematic method of naming organic chemical compounds as recommended by the International Union of Pure and Applied Chemistry (IUPAC).

The case where there is 6 months day, and 6 months night could only happen on poles because The Earth is tilted on its axis.

The pole which is away (opposite direction of sun) from the Sun remains in complete darkness till it comes in front of the sun.

So we conclude that, countries at the poles have 6 months day, and 6 months night.

So countries close to these region have such cases like, Alaska, Antarctica, Norway etc.

Norway, the northernmost inhabited region of Europe, there is no sunset from approximately 19 April to 23 August. The extreme sites are the poles, where the sun can be continuously visible for half the year. The North Pole has midnight sun for 6 months from late March to late September.

If we consider the given numbers  6, 4, 9, 10, 11 to be the month number then we can easily find the killer.

6 – June – J

4 – April – A

9 – September – S

10 – October – O

11 – November – N

Hence the answer is JOEL.

Both Formaldehyde and Acetaldehyde will give this test

 HCHO→[Ag(NH3)2+] Silver mirrorAg + Organic compound

 CH3-CHO →[Ag(NH3)2+] AgSilver mirror+ Organic compound