1. You are given a series circuit with three identical light bulbs. Each bulb has a resistance of (4.40x10^0) ohms. The circuit is connected to a power supply of (1.0800x10^1) V. Using Ohm's Law, calculate the current flowing through it. Present your answers with three significant figures and the appropriate units.

2. Calculate the radius of the electron in the hydrogen atom when it is in the (8.00x10^0)th orbit. Express your answer in nanometers (nm) with three significant figures.

3. A radioactive sample of a certain element has an initial mass of 150 grams. The half-life of this element is 20 years. Calculate the remaining mass of the sample in grams (g) after (3.00x10^0) half-lives have passed.

4. What is the formula mass of methane (CH₄), given that the mass of carbon (C) is 12.01 u (atomic mass units) and the mass of hydrogen (H) is 1.008 u?

Please provide the details of your calculations and express your answer to three significant figures, including the appropriate units.

5. Given the element magnesium on the periodic table, determine its

• atomic mass in amu (to five decimal places),
• atomic number,
• number of protons,
• and number of electrons.