How many significant figures are in the number 2011

Bill and Mary wanted to have a snack after school. They heated some milk in a pot on the stove to make hot chocolate. They also popped some popcorn in the microwave oven.

9. How many electrons are in the highest energy orbital of the element copper?

The pressure system begins at 99.7 kpa. the volume of the gas is 150ml. What would be the final volume in the system if the pressure drops to 99.8 Kpa?

A sample of gas contains 0.1700 mol of NH3 (g) and 0.2125 mol of O2 (g) and occupies a volume of 17.8 L.

Which statement about the energy of a phase change is true? A. Melting is an endothermic change, because ice releases energy to its surroundings as it melts. B.

Assume 3 molecules of Fe react according to the following equation. 3Fe + 4H2O Fe3O4 + 4H2 How many molecules of H2 are produced? How many water molecules are required? What is the mole ratio of Fe to H2O?

10.0 mL of a HF solution was titrated with a 0.120 N solution of KOH; 29.6 mL of KOH were required to completely neutralize the HF. Calculate the normality of the HF solution.

The number of grams present in 1.35 mol of Fe is

Which can associate a suspect's gun with a crime?

In which era did the first fish appear? a. Carboniferous b. Paleozoic C. Mesozoic d. Permian