4. Thorium-234 has a half-life of 24.1 days. What percentage of the original thorium-234 in a sample will remain after 144.6 days?

What is the final temperature of 78g sample of water at 99°C if it loses 6500 J of heat energy?

How many years can it take plastic bottle to break down?

Which clue can be used to identify a chemical reaction as a combustion reaction? Oxygen is a product. A hydrocarbon reacts with oxygen. Water and carbon dioxide react. The reaction involves ions.

How to calculate energy change in a reaction

A sample of brass, which has a specific heat capacity of 0.375 J*g^-1*°C^-1 is put into a calorimeter (see sketch at right) that contains 250.0 g of water. The brass sample starts off at 85.7°C and the temperature of the water starts off at 16.0 °C.

Every water molecule has two hydrogen atoms bonded at one oxygen atom. This fact supports the concept that elements in a compound are

What is the mass of 9 atom (s) of copper in grams?

Andy has two samples of liquids. Sample A has pH of 4, and sample B has a pH of 6. what can Andy conclude about these two samples? Sample A is a neutral b alkali c acidic Sample B is a neutral b alkali c acidic

How does a lone pair contribute to molecular shape? A. It is too small to affect the molecule's shape. B. It takes up space like an "invisible" atom. C. It forces the molecule into a tetrahedral shape. D. It lets the bonding pairs spread out more.

The are of a rectangle is 12 in^2. what is the area in cm^2. there are 2.54cm in an inch.