A number placed in front of an element symbol

What elements are denser than air

Describe two chemical reactions that require energy in order to occur

Why can solids undergo convection

How does refrigeration keep food fresher? 1) Cold air surrounds food and slows the spoiling process. 2) It speeds up reaction rates within stored food. 3) It slows down reaction rates within stored food. 4) It causes food molecules to stop vibrating.

Which statement best explains why carbon is present in so many kinds of molecules? it has valence electrons. it can form four covalent bonds. it is abundant on earth. it can become an ion.

What effect does distance have on the strength of the force of gravity

A compound contains 40.0% carbon, 6.7% hydrogen, and 53.3% oxygen (by mass). calculate the empirical formula.

100 g of water and 100g of metal sample are heated from 25 to 75. which substance requires more thermal energy to reach 75c

A process or reaction which takes in heat from the surroundings is said to be

What is the volume of 0.05 mol of neon gas at STP?