Why do we add isopropyl alcohol to the tube of DNA, and what is the result?

To achieve precipitation of the DNA.

Explanation:

Isopropyl alcohol makes the DNA sediment. The DNA, once out of the solution, becomes visible, as it clumps.

The result of adding isopropyl alcohol is the precipitation or sedimentation of DNA when DNA becomes like a visible thread with the help of alcohol and salt. The precipitation of DNA is important because it removes the dirt from DNA.

Option (2)

Explanation:

Celtic runes sites refers to some of the places in the northern part of Europe whose common scripts are the Celtic runes.

The remnants of wooden structures are discovered in this place by the scientists, and in order to determine the time, that is, when the stones were carried by the Celts into the mentioned place, the most efficient way of determining this time will be the carbon dating method.

The carbon dating method is efficiently used to date an object that are of very recent age. It is because the half life of carbon is approximately 5700 years, which is geologically a very small age.

Thus, the correct answer is option (2).