Which of the following is an example of an irreversible physical change? A. Melting a piece of lead B. Boiling water C. Sharpening a pencil D. Dissolving sugar into water

A student had 1.00 L of a 1.00 M acid solution. Much to the surprise of the student, it took 2.00 L of 1.00 M NaOH solution to react completely with the acid. Explain why it took twice as much NaOH to react with all of the acid.

You have 80 g of a radioisotope. If the half-life of this radioisotope is 4 days, how many grams will remain after 16 days? Must show work or reasoning for full credit

Hydrogen is used as a rocket fuel because it is very light and reacts explosively and completely with oxygen. For the combustion reaction 2H2 (g) + O2 (g) ⇌2H2O (g) what is the likely magnitude of the equilibrium constant K? 1. K<10-3 2. 10-3 3.

A cup of cocoa is left on the counter. Which best describes how its temperature changes? a) the heat leaves the cup of cocoa b) cold enters the cup of cocoa c) the molecules in the cocoa speed up d) the temperature will not change

If you have 8.46x10^24 atoms of calcium, how many grams of calcium do you have?

Two children are playing tag. Child A who is doing the chasing can run 100m in 24 seconds Child B is running away from child A and can run 64m in 21 seconds.

What ion does a base increase

What is the definition of Amplitude?

An excess of NiCO3, 12 g, was added to 40cm cube of sulpheric acid, 2.0 mol/dm cube. The unreacted nickel carbonate was filtered out and the filtrate evaporated to optain the crystals.

Under what condition is decompostion the fastest? Under what condition is it the slowest?