Across

1. the alkali metal in Period 4

What are the problems with studying the structure of the earth?

How did Niels Bohr describe electrons in his atomic model A. Their energies can have any values B. Their exact positions cannot be known C. They have high probability to be found in certain regions D. They orbit the central nucleus in discrete paths

Calcium hydride (CaH2) reacts with water to form hydrogen gas: CaH2 (s) + 2H2O (l) → Ca (OH) 2 (aq) + 2H2 (g) How many grams of CaH2 are needed to generate 45.0 L of H2 gas at a pressure of 0.995 atm and a temperature of 32 °C?

Which is an example of an atom? A) The smallest unit of Ne. Eliminate B) The smallest unit of P4. C) The smallest unit of NH3. D) The smallest unit of H2O.

Leslie is observing the air in a balloon. She wants to know if the air in the balloon is matter. What must be true of the air for it to be matter?

2. An object experiences an acceleration, g, when it is on the surface of a planet of radius R. What will be the acceleration on the object after it has been moved to a distance of 4R from the center of the planet? A) 168 B) 48 C) 1/4 g D) 1/16 g

For a successful TLC experiment, you need to pay attention to the details. From the list of instructions and tips below, select the detail that is NOT important to a TLC experiment. O O Do not disturb the developing chamber.

The word atom means invisible?

A pycnometer weighs 25.60 g empty and 35.55 g when filled with water at 20°C. The density of water at 20°C is 0.9982 g/ml. When 10.20 g lead is placed in the pycnometer and the pycnometer is again filled with water at 20°C, the total mass is 44.83 g.

How does weathering affect the surface area of a rock? Explain your answer.