CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which method can separate an insoluble solid from a liquid?
A. Filtration
B. Chromatography only
C. Distillation only
D. Sublimation only
Correct Answer: A
Filtration traps insoluble solid particles while the liquid passes through.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which is an example of a heterogeneous mixture?
A. Oil and water
B. Sugar solution
C. Brass
D. Air
Correct Answer: A
Oil and water form separate phases and are not uniform.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
Which is an example of a homogeneous mixture?
A. Salt solution
B. Sand and iron filings
C. Granite
D. Oil and water
Correct Answer: A
A salt solution has uniform composition at the macroscopic scale.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Mixtures
What is a mixture?
A. A compound with fixed bonding
B. A substance with only one atom type
C. A single element only
D. A physical combination of substances in which components retain their chemical identities
Correct Answer: D
Mixtures are formed physically and can often be separated by physical methods.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
What law explains the fixed elemental composition of a pure compound?
A. Snell's law
B. Law of definite proportions
C. Boyle's law
D. Ohm's law
Correct Answer: B
A given pure compound contains the same elements in the same proportion by mass.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Which type of bond involves sharing electron pairs?
A. Covalent bond
B. Ionic bond only
C. Nuclear bond
D. Gravitational bond
Correct Answer: A
Covalent bonds form when atoms share electron pairs.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Which type of bond forms by transfer of electrons between atoms, as in many salts?
A. Covalent bond only
B. Ionic bond
C. Metallic bond only
D. Hydrogen bond only
Correct Answer: B
Ionic bonding arises from electrostatic attraction between oppositely charged ions formed by electron transfer.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Carbon dioxide contains which elements?
A. Calcium and oxygen
B. Carbon and oxygen
C. Carbon and nitrogen
D. Hydrogen and oxygen
Correct Answer: B
CO2 contains carbon and oxygen.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Which statement distinguishes compounds from mixtures?
A. Mixtures always have fixed composition
B. Mixtures cannot contain elements
C. Compounds have elements chemically bonded in fixed proportions
D. Compounds always contain only two atoms
Correct Answer: C
Mixtures can have variable composition; compounds have fixed stoichiometric ratios.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
What is the chemical formula of common salt, sodium chloride?
A. NaCO3
B. KCl
C. Na2Cl
D. NaCl
Correct Answer: D
Sodium chloride consists of sodium and chloride ions in a 1:1 ratio.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
What is the chemical formula of water?
A. O2H4
B. HO2
C. H2O
D. H2O2
Correct Answer: C
Each water molecule contains two hydrogen atoms and one oxygen atom.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Can the components of a compound usually be separated by simple physical methods such as filtration?
A. Only if solid
B. No
C. Yes, always
D. Only if colored
Correct Answer: B
Breaking a compound into constituent substances generally requires chemical change.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
Which is a compound?
A. Iron
B. Water
C. Oxygen
D. Helium
Correct Answer: B
Water consists of hydrogen and oxygen chemically combined as H2O.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Compounds
What is a compound?
A. A pure substance formed when two or more elements are chemically combined in fixed proportions
B. A solution with variable composition
C. Any physical mixture
D. A single atom only
Correct Answer: A
Compounds have definite composition and chemically bonded elements.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which class of elements generally conducts heat and electricity well?
A. Metals
B. Halogens only
C. Noble gases only
D. Nonmetals only
Correct Answer: A
Metals typically have mobile electrons that enable good electrical and thermal conduction.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Elements in the same vertical column of the periodic table are called a what?
A. Series only
B. Isotope
C. Period
D. Group
Correct Answer: D
Vertical columns in the periodic table are groups.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which element is the most abundant in the universe?
A. Silicon
B. Hydrogen
C. Iron
D. Oxygen
Correct Answer: B
Hydrogen is by far the most abundant element in the universe.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which element is the most abundant in Earth's atmosphere by volume?
A. Hydrogen
B. Nitrogen
C. Oxygen
D. Carbon
Correct Answer: B
Dry air is about 78% nitrogen by volume.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which symbol represents iron?
A. Fe
B. Ir
C. I
D. In
Correct Answer: A
Iron's symbol Fe comes from Latin ferrum.
CSS - PMS - CCE - PCS - General Science
Basic Chemistry - Elements
Which symbol represents the element sodium?
A. Na
B. Sd
C. So
D. S
Correct Answer: A
The chemical symbol for sodium is Na, from Latin natrium.