1-7 Describe naturally-occurring forms of elements

1-7-1. Which of the following elements is the best electrical conductor?
A. carbon, B. germanium, C. manganese, D. iodine

1-7-2. Which of these naturally occurs as a monatomic gas under ordinary conditions?
A. helium, B. sodium, C. oxygen, D. nitrogen

1-7-3. Which of these elements naturally occurs as a diatomic gas under ordinary conditions?
A. bromine, B. iodine, C. mercury, D. chlorine

1-7-4. Which of these elements is not a gas under ordinary conditions?
A. bromine, B. helium, C. hydrogen, D. oxygen