I can’t figure it out!

Express the following number in scientific notation. 0.026890 =

24. a sports ball is inflated to an internal pressure of 1.85 atm at room temperature (25 °c). if the ball is then played with outside where the temperature is 7.5 °c, what will be the new pressure of the ball? assume the ball does not change in volume nor does any air leak from the ball a) 0.555 atm b) 1.74 atm c) 1.85 atm d) 1.97 atm

What is the empirical formula of c6h18o3? ch3o c2h5o c2h6o c2h5o5