How would you write 1.6340 x 10⁴ in scientific notation with 2 significant figures?

Can someone me with questions 12 and 13 plz.

In which of the following phases of matter do molecules have the highest amount of energy? a. liquid b. gel c. solid d. gas

If you need to add 27.50ml of a solution, which piece of glassware would you use to deliver this volume and explain how you would determine if the 27.50 ml was measured?