For a1, its atomic number is 13 and its mass number is 27 how many neutrons does it have?

What type of electromagnetic wave is used in security pens? a. X-rays b. Visible light c. Microwaves d. Ultraviolet radiation

What distinguishes effusion from diffision? How are these processes similar?

Select the correct answer Which statement correctly describes a physical change? A involves breaking and creating chemical bonds but not changing a phase B. may involve a change in phase but does not involve a change in the molecular structure C.

Any time an atom transfers or shares an electron a is formed

If an engineers greatest concern is easy maintanance of a rocket throughout the years, the rocket should be designed to use which type of fuel?

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.

Are energy levels and orbitals the same thing?