Chemical Reactions Physical Science

In a chemical equation, is it true that -

• the reactant side and product side can have different numbers of atoms for each element
• there can be different elements on the reactant side and the product side
• an element or compound must be accompanied by a phase change
• the coefficients indicate the number of molecules of each reactant used and the number of molecules of each product made

Chemical energy is a form of

• potential energy

• light energy

• kinetic energy

• infinite energy

Which of the following models best demonstrates a balanced chemical equation?

• F
• G
• H
• J

The reactants are on the left (<--) side of the chemical equation.

• True
• False

Coal contains carbon and other elements. Carbon dioxide forms when coal burns in the presence of oxygen. Which of these is the best evidence that a chemical reaction occurs when coal burns?

• The shape of the coal changes
• Oxygen is present
• A new substance is produced
• Coal is made up of more than one element

What is the left part of a chemical equation called?
H_{2 +} O → H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

When a chemical reaction occurs, the products have a different amount of chemical energy than the reactants because

• the atoms are moving at a different speed

• there are a different number of them

• the atoms are arranged differently (different bonds)

• the atoms are different elements

Is this balanced?
2HgO → 2Hg + O₂

• Yes
• No

Is this balanced?
Al + O₂ → 2Al₂O₃

• Yes
• No

Energy is always _____ in a chemical reactions.

• gained

• lost

• conserved