what type of solder do I have in this picture?
You can get some idea of the composition by looking at the melting temperature if you have a digital iron and at whether it solidifies suddenly or has a "mushy" range that makes it easy to get "cold" solder joints if the melt is disturbed as it is solidifying. 

Plumbing solder was usually 50:50 Sn-Pb so it has a high melting range (183–215°C) and the alloy is far from eutectic. 60:40 Sn-Pb was used for electronics (183–190°C)

Eutectic Sn63Pb37 solder has a sharp melting point at 183°C. 

If there is an unknown flux core in that solder it could be acid core, and very destructive to electronics (and even more so when power is applied).