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.