The answer is Selenium.
Hope that helps.
Answer:
690 g IrI₃
Explanation:
To convert from moles to grams, you have to use the molar mass of the compound. The molar mass of IrI₃ is 572.92 g/mol. You use this as the unit converter in this equation:

Round to the lowest number of significant figures which is 2 to get 690 g IrI₃.
Answer:
Option D
Oxygen particles mix evenly with hydrogen particles.
Explanation:
Diffusion refers to the movement of gasses from a region of higher concentration to a region of lower concentration.
Diffusion occurs in gases because their particles are in a state of constant random motion.
Due to this continuous random motion, once the oxygen and the hydrogen are added to the container, they will begin to mix freely with each other until they fill up the entire volume of the container.