The symbol Ca-40 denotes that

A. a calcium atom contains 40 protons

B. a calcium atom contains 40 electrons

C. a calcium atom contains 40 neutrons

D. a calcium atom has a mass number of 40

How many significant figures are in the measurement 0.020 km?

How have chemists changed the periodic table over time? Apex

Seafood Watch has made several unsustainable fishing practices illegal. true or false

A 1 mol sample of gas has a temperature of 225K, a volume of 3.3L, and a pressure of 500 torr. What would the temperature be if the amount of gas remains constant while pressure dropped to 210 torr, and the volume dropped to 2.75L?

Based in the rules of John Dalton, what is a possible hypothesis that could be tested in the Atomic Theory lab?

How much water should be added to 20 ml of 20 % alcohol solution to reduce the concentration to 10 %?

Calculate the theoretical atom economy for each reaction. a. 2 cuo (s) + c (s) → 2 cu (s) + co2 (g)

In the coordination compound (NH4) 2[Fe (OH2) F5], the Fe is octahedrally coordinated. (a) Based on the fact that F is a weak-field ligand, pre - dict whether this compound is diamagnetic or para - magnetic.

Which of these is a good conductor? 1) wood 2) air 3 ) silver 4) paper

Explain the energy transformation that must occur for your body to participate in a physical activity, such as playing a sport.