CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Can an element be decomposed into simpler substances by ordinary chemical means?
A. Only by filtration
B. No
C. Yes, always
D. Only in water
Correct Answer: B
An element cannot be broken into simpler substances by ordinary chemical reactions.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which is an example of an element?
A. Sodium chloride
B. Oxygen
C. Water
D. Carbon dioxide
Correct Answer: B
Oxygen is an element; the others are compounds.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
What is a chemical element?
A. A solution that can be filtered
B. A pure substance made of atoms with the same number of protons
C. A compound containing carbon only
D. A mixture of any two substances
Correct Answer: B
An element is defined by a unique atomic number, or proton count.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which physical property is defined as mass per unit volume?
A. Pressure
B. Density
C. Viscosity
D. Temperature
Correct Answer: B
Density is calculated as mass divided by volume.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which property is generally conserved during an ordinary chemical reaction in a closed system?
A. Mass
B. Color
C. Shape
D. Volume in all cases
Correct Answer: A
The law of conservation of mass applies to ordinary chemical reactions in closed systems.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which state of matter consists largely of ions and free electrons?
A. Bose glass only
B. Plasma
C. Solid
D. Liquid
Correct Answer: B
Plasma is an ionized state containing charged particles.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
What is the change from liquid to gas at the surface below boiling point called?
A. Freezing
B. Deposition
C. Evaporation
D. Solidification
Correct Answer: C
Evaporation is a surface phenomenon that can occur below the boiling point.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
What is the change from gas to liquid called?
A. Evaporation
B. Condensation
C. Sublimation
D. Fusion
Correct Answer: B
Condensation occurs when gas particles lose energy and form a liquid.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
What is the change from solid directly to gas called?
A. Freezing
B. Melting
C. Condensation
D. Sublimation
Correct Answer: D
Sublimation bypasses the liquid phase.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which state of matter has neither a fixed shape nor a fixed volume?
A. Solid
B. Crystal only
C. Liquid
D. Gas
Correct Answer: D
A gas expands to fill its container.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which state of matter has a definite volume but takes the shape of its container?
A. Solid
B. Gas
C. Vacuum
D. Liquid
Correct Answer: D
Liquids flow and adopt container shape while remaining nearly incompressible.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which state of matter has a definite shape and definite volume?
A. Plasma only
B. Liquid
C. Gas
D. Solid
Correct Answer: D
Particles in a solid remain in fixed relative positions, giving a definite shape and volume.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Matter
Which definition best describes matter?
A. Anything that emits light
B. Anything that has mass and occupies space
C. Only substances visible to the eye
D. Only solids
Correct Answer: B
Matter has mass and occupies volume.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
Why can multiple protons remain bound in a nucleus despite electrostatic repulsion?
A. Protons become electrically neutral in nuclei
B. Gravity dominates at nuclear scale
C. The strong nuclear force can overcome repulsion at very short distances
D. Electrons sit between every pair of protons
Correct Answer: C
The attractive strong nuclear interaction is dominant over very short nuclear distances.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
Which force causes electrostatic repulsion between protons in a nucleus?
A. Friction
B. Electromagnetic force
C. Strong force only
D. Gravity only
Correct Answer: B
Like positive charges repel through the electromagnetic interaction.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
Which particle is the nucleus of ordinary hydrogen and is also emitted in some nuclear reactions?
A. Proton
B. Photon
C. Electron
D. Neutrino
Correct Answer: A
A hydrogen-1 nucleus consists of one proton.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
Which nucleus contains exactly one proton and no neutron?
A. Deuterium
B. Helium-4
C. Hydrogen-1
D. Carbon-12
Correct Answer: C
The protium nucleus is a single proton.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
A neutral atom with 17 protons contains how many electrons?
A. 17
B. 18
C. 34
D. 16
Correct Answer: A
Electrical neutrality requires equal numbers of protons and electrons.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
Approximately how much mass does a proton have in atomic mass units?
A. Exactly 0 u
B. About 1 u
C. About 0.0005 u
D. About 100 u
Correct Answer: B
A proton has a mass close to one unified atomic mass unit.
CSS - PMS - CCE - PCS - General Science
Atomic Structure - Protons
What happens to elemental identity when proton number changes?
A. Only electron charge changes
B. Only the isotope changes
C. The atom becomes a different element
D. Nothing changes
Correct Answer: C
Element identity is determined by atomic number, which equals proton number.