How many valence electrons does selenium have?

2. Answer the following questions about a sample of calcium phosphate: a. What is the molecular weight of Ca3 (PO4) 2? b. How many moles of Ca3 (PO4) 2are in 1350g? c. How many molecules of Ca3 (PO4) 2 are there in 1350g? d.

How do metal atoms bond with one another?

What are the uses of chemistry?

State two ways in which a single-called organism, such as amoeba, and a human body cell are alike

By studying a star's spectrum, scientists can work out its chemical make-up and temperature. What instrument do astronomers' use to carry out this task? A) space probe B) spectroscope C) radio telescope D) light telescope

Which is the balanced chemical equation showing hydrogen peroxide (h2o2) decomposing into hydrogen (h2) and oxygen (o2) ? 1. h2 + o2 → h2o2 2. 2 h2o2 → 2 h2 + o2 3. h2o2 → h2 + o2 4. 2 h2 + o2 → 2 h2o2?

Assuming constant pressure, rank these reactions from most energy released by the system to most energy absorbed by the system, based on the following descriptions: A. Surroundings get colder and the system decreases in volume. B.

Zircon is a mineral with the empirical formula ZrSiO4. If all the zirconium is 90Zr, all the silicon is 28Si, and all the oxygen is 16O, what mass of oxygen is present in 10. g of zircon?

Which property below is not a general property of metals: A. Ductile C. Malleable B. Poor conductor of heat D. High luster

Calculate the number of particles (atoms or molecules) of the following: 1. How many molecules are there in 24 grams of FeF3? 2. How many molecules are there in 450 grams of Na2SO4? 3. How many grams are there in 2.3 x 1024 atoms of silver?