8 physics questions help!?

1. A element is a substance that ____

A. Found only in solids and liquids

B. Cannot be broken down into simpler substances by chemical means

C. Is composed of two or more different atoms

D. Cannot react with another substance to create a third substance.

2. Alpha particals can be stopped by

A. Concrete

B. Aluminum

C. Paper

D. Lead

3. A transformer _______.

A. Is a large wheel that rotates when pushed by water wind or stream

B. Is a device that uses an electromagnet to measure electric current

C. Changes electrical energy into mechanical energy

D. Increases or decreases the voltage of an alternating current

4. Chemical reactions involve the breaking of chemical bonds in the reactants and the _______ of chemical bonds in the products.

A. Break down

B. Substitution

C. Formation

D. Disappearing

5. What two substances are always produced by a neutralization reaction?

A. Water and Salt

B. Water and acid

C. Water and a base

D. Acid and a base

6. Isotopes have:

A. same number of protons but different number of electrons

B. Same number of electrons but different number of protons

C. Same number of protons but different number of neutrons

D. Same number of neutrons but different number of protons

7. Which of these is necessary in order to make an electric circuit?

A. Light bulb

B. Closed path

C. Battery

D. Copper wire

8. Dot diagrams are used to represent ___

A. Outer electrons

B. Atomic number

C. Isotopes

D. Structure of nucleus