Waleed is learning about symbols for atoms and ions. He knows that the symbol for a sodium ion is Na+. What does the '+' sign indicate?

Which property depends on amount of matter?

Hina is learning about environmental chemistry. She understands that it studies the chemical processes occurring in the environment. Which of the following issues is most relevant to environmental chemistry?

Xia is studying the history of atomic models. She learns that the quantum mechanical model is based on the wave-particle duality of electrons. Who proposed this concept?

Vera is studying how solar energy can be harnessed. She learns about photovoltaic cells that convert sunlight into electricity. Which branch of chemistry is involved in developing photovoltaic materials?

Julia is studying the properties of matter. She notices that a liquid can flow and take the shape of its container. This property is known as:

Tina has a solution of potassium permanganate in water. The solution is purple and uniform. If she adds more water, the solution becomes lighter. What is happening to the concentration?

Which element has the largest atomic radius?

Zayn is studying the behavior of protons in an electric field. He learns that protons are deflected towards the negative plate. What does this indicate about the proton?

Atomic number is equal to the number of: