What is the atomic number of Uranium? 

92

The correct answer is option 2. 92.

The atomic number of an element represents the number of protons in the nucleus of an atom of that element. For uranium, the atomic number is 92. This means that a neutral atom of uranium has 92 protons.

Uranium is a chemical element with the symbol U, and it is a heavy, radioactive metal. It belongs to the actinide series on the periodic table and is located in period 7, group 3. Uranium has several isotopes, with uranium-238 (U-238) being the most abundant in nature.

The atomic number is a fundamental property of an element and determines its unique place on the periodic table. It also dictates the number of electrons in a neutral atom of that element, as the number of electrons is equal to the number of protons. In the case of uranium, the atomic number 92 signifies its position as the 92nd element in the periodic table.