The symbol Ca-40 denotes that

A. a calcium atom contains 40 protons

B. a calcium atom contains 40 electrons

C. a calcium atom contains 40 neutrons

D. a calcium atom has a mass number of 40

Which category of galaxy dose not have a distinactive shape A a barred - spiral galaxy Ba spiral galaxy C an elliptical galaxy D an irregular galaxy

In the food chain what might happen if all the frogs suddenly died off?

Does a solution have to involve a liquid? explain.

How do I convert Kilometers to miles? And Kg to pounds?

Matt's cube, after 5 trials, had an average density of 7.40 g/cm3. His group's cube was made of A) aluminum. B) gold. C) nickel. D) zinc.

Of the following, which is most likely to result after a farmer sprays his crops with pesticides? A. The crops die. B. The insect population increases. C. The soil dries up and blows away. D. A neighbor's well tests positive for pesticides.

How many liters does the following number of atoms of helium take up? 9.42x10^22 atoms He

Why isn't biuret reagent required for determining the absorption spectrum of hemoglobin?

During which phase change does the arrangement of water molecules become more orderly A.) melting B.) subliming C.) boiling D.) condensing

What's the difference between Mixture and Solution?