In an exothermic reaction what is true of enthalpy?

A) it has increased

B) it has decreased

C) it has remained unchanged

D) it has a minimum doubled

According to one acid-base theory a molecule acts as an acid when the molecule

What is true about energy in an ordinary chemical reaction? Energy is created during the reaction. destroyed if there is an explosion. not created or destroyed. used up by the reaction.

What accounts for most of an atoms volume

How do structures stand up under a load

iron has a density of 7.874 g/mL. if a sample of iron has a mass of 7.75 grams, what is the volume of this sample in dL

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.

Which statements describe advantages of models? Check all that apply. Models make it possible to easily notice patterns. Models can be used to communicate and test design ideas. Models allow scientists to predict relationships.