Science 8 - Review Questions for Term Exam

Which of the following is NOT true about the kinetic particle theory?

• It believes that all matter is made of tiny particles.

• It explains the particles of a matter are in random and constant motion.

• It states that particles of a matter can still be broken down into smaller piece.

• It asserts that there are attractive forces between particles of a matter.

Answer explanation

Kinetic Particle Theory states that:

1. All matter is made up of tiny particles

2. There are attractive forces between the particles.

3. The particles are in constant and random motion.

What is the CORRECT explanation for the condition of the particles of a matter that underwent deposition? (You must have two answers)

• The particles become loose and disorder.

• The particles become compact and arrange in orderly manner.

• The attractive force between particles become stronger disabling them to move freely.

• The attractive force between each particle weakens allowing them to move freely.

Answer explanation

When a matter undergoes deposition, its particles become compact and arranged orderly due to the stronger attractive forces. On the other, the decrease in the amount of kinetic energy among particles limits their motion.

Which of the following does NOT belong to the group?

• freezing

• sublimation

• deposition

• condensation

Answer explanation

In the processes of freezing, condensation, and deposition, heat is released to initiate phase change.

In the processes of melting, evaporation, and sublimation, heat is absorbed to initiate phase change.

Which of the following is a by-product of sublimation?

• Purple gas formed after solid iodine was heated.

• Snow flakes formed due to the extreme low temperature.

• ice cubes were formed in the freezer.

• Rain poured out from clouds.

Answer explanation

Purple gas from iodine was the result of sublimation.

Snowflakes were the result of deposition.

Ice cubes were the result of freezing.

Rain was the result of condensation.

Which of the following substances will boil the slowest?

• 5-L of tap water

• 500-mL of orange juice

• 1 kL of saltwater

• 700-mL of vinegar

Answer explanation

Remember that the boiling point of water (liquid) is 100 degrees Celsius. The choices, all have the same boiling point, however, the amount of the liquid is the factor here that could determine which one will boil the fastest and the slowest. 1 kL of saltwater is the answers probably because of its amount.

Which of the following subatomic particles has a positive (+) electric charge?

• neutron

• electron

• proton

• none of the above

Answer explanation

A proton has an electric charge of positive one (+1).

An electron has an electric charge of a negative one (-1).

A neutron has no net electric charge.

Which of the following model believes that elements are made up of tiny indivisible or uncuttable particles that consistently move?

• Planetary Model of an Atom

• Plum-Pudding Model

• Quantum Mechanical Model

• Indivisible Model

Answer explanation

Indivisible Model (Democritus) - Element is made up of tiny indivisible or uncuttable particles that consistently moving

Planetary Model of Atom (Neils Bohr) - electrons encircle the nucleus of the atom in specific allowable paths called orbits.

Plum-Pudding Model (JJ Thompson) -defined by electrons surrounded by a volume of positive charge, like negatively-charged “plums” embedded in a positively-charged “pudding”.

Quantum Mechanic

Model (Erwin Schrodinger) - specifies the probability of finding an electron in the three-dimensional space around the nucleus

Who discovered neutrons?

• James Chadwick

• Ernest Rutherford

• Eugen Goldstein

• JJ Thompson

Answer explanation

Neutron was discovered by James Chadwick in 1932.

Proton was discovered by Ernest Rutherford.

Electron was discovered by JJ Thompson.

Which of the following is TRUE about the mass of an atom?

• It is based on the weight of protons and neutrons in the nucleus.

• It is equal to the sum of all electrons in each shell.

• It is based on the weight of electrons and protons.

• It is equal to the sum of all subatomic particles in the atom.

Answer explanation

The ATOMIC MASS is equivalent to the sum of the number of protons and neutrons in an atom.

Complete the table with the missing information about the element.

• Atomic mass = 56

  Number of protons = 31

• Atomic mass = 28

  Number of protons =28

• Atomic mass = 59

  Number of protons = 28

• Atomic mass = 31

  Number of protons = 59

Answer explanation

"A" represents the atomic mass, while p⁺ represents the number of protons.

The number of protons is simply the same as the atomic number (Z) and a number of electrons (e^-).

Since the number of electrons is 28 thus protons are also 28.

To get the atomic mass, simply get the sum of the number of protons and neutrons. (A = p⁺ + n^o)

Solution:

A = 28 + 31

A = 59