PRACTICE

which of the following is a physical change?

• Burning magnesium

• Rusting of iron

• Melting ice

• Reaction of acid with metal

In solids, particles:

• Are far apart and move freely

• Vibrate around fixed positions

• Move randomly at high speed

• Slide over each other

Diffusion occurs fastest in:

• Solids

• Liquids

• Gases

• Metals

Which subatomic particle has a positive charge?

• Electron

• Proton

• Neutron

• Positron

The nucleus of an atom contains:

• Elec + Pro

• Elec + Neu

• Pro + Neu

• Only elec

The number of protons in an atom equals the:

• A. Mass number

• B. Number of neutrons

• C. Atomic number

• D. Electron shell number

The relative mass of a neutron is approximately:

• A. 0

• B. 1

• C. 2

• D. 0.0005

Isotopes of an element differ in:

• A. Proton number

• B. Neutron number

• C. Electron number

• D. Atomic number

Which gas is monatomic?

• A. Oxygen

• B. Chlorine

• C. Helium

• D. Hydrogen

The electron configuration of oxygen is:

• A. 2,8

• B. 2,6

• C. 2,7

• D. 2,5