A sample of Strontium-90 is found to have decayed to one-fourth of its original amount after 58.2 years. What is the half-life of strontium-90?

Looking at the same nonmetal group on the periodic table, how does the reactivity of an element in period 2 compare to the reactivity of an element in period 4?

The particles that are found in the mucleus of an atom are 1. neutrons 2. electrons only 3. protons and neutrons 4. protons and electrons

The last column of the periodic table contains the noble gases elements that do not easily form chemical bonds. Why don't these gases tend to form chemical bonds?

Explain how electrically neutral objects can become electrically charged even though charge cannot be created or destroyed.

Which of the following best explains why arginine is more basic than lysine? A. The electron-donating groups around the basic nitrogen on arginine make its conjugate base less stable. B.

How does a mixture of benzoic acid and benzaldehyde can be isolated separately by extractions?

What is a compound? a) a combination of two or more substances that are not chemically combined b) a combination of two or more elements that are combined in a certain ratio

A gas has a volume of 75mL at a pressure of 200.0 kPa. What will be the new volume be in mL if the pressure is decreased to 60.0 kPa in sig figs

Give two reasons why it's important to work with a partner in a lab

Suppose you have 3.00*1018 reams of lead (pb). how many lead atoms do you have? express the number of atoms numerically.