BRAINLIEST IF CORRECT HURRY 4. Which of the following is true about lanthanides?
a. They have low melting and boiling points.
b. They are very common elements.
c. They are highly electropositive.
d. They are all radioactive.

5. How can the atomic orbital be described in the quantum mechanical wave model of the orbitals?
a, A collection of balloons
b. A planetary orbital
c. A probability density
d. A circular ring

9. Which of the following elements is the most electronegative: aluminum, beryllium, oxygen, or fluorine?
a. aluminum
b. fluorine
c. oxygen
d. beryllium