CSS - PMS - CCE - PCS - General Science
Biodiversity
Which level refers to the variety of habitats, communities and ecological processes?
A. Atomic diversity
B. Ecosystem diversity
C. Cultural diversity only
D. Protein diversity
Correct Answer: B
Ecosystem diversity includes different ecosystems and ecological interactions.
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Biodiversity
Which level describes the variety of different species in an area?
A. Species diversity
B. Geological diversity
C. Chemical diversity
D. Genetic diversity only
Correct Answer: A
Species diversity concerns the richness and relative abundance of species.
CSS - PMS - CCE - PCS - General Science
Biodiversity
Which level of biodiversity describes variation in genes within a species?
A. Mineral diversity
B. Ecosystem diversity
C. Atmospheric diversity
D. Genetic diversity
Correct Answer: D
Genetic diversity is variation in inherited genetic information within or among populations.
CSS - PMS - CCE - PCS - General Science
Biodiversity
What does biodiversity refer to?
A. The variety of life at genetic, species and ecosystem levels
B. Only animal body size
C. Only climate zones
D. Only the number of trees
Correct Answer: A
Biodiversity includes variation within species, among species and among ecosystems.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
In calcium oxide, CaO, what is the valency of calcium?
A. 3
B. 1
C. 4
D. 2
Correct Answer: D
Calcium forms Ca2+ and oxygen forms O2−, producing a 1:1 formula.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
Which term is more precise than fixed valency for transition metals that can form ions with different charges?
A. Boiling point
B. Atomic radius only
C. Isotope number
D. Oxidation state
Correct Answer: D
Transition metals often exhibit multiple oxidation states.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the valency of magnesium in magnesium chloride, MgCl2?
A. 2
B. 3
C. 1
D. 4
Correct Answer: A
Magnesium forms Mg2+ and has valency 2 in this compound.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the valency of sodium in sodium chloride?
A. 1
B. 2
C. 0
D. 3
Correct Answer: A
Sodium loses one valence electron to form Na+.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
Why do noble gases generally have valency zero in elementary descriptions?
A. Their outer electron shells are already stable and complete
B. They are all metals
C. They have no nuclei
D. They contain no electrons
Correct Answer: A
Closed-shell electron configurations make noble gases relatively unreactive.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the usual valency of carbon in methane, CH4?
A. 2
B. 3
C. 1
D. 4
Correct Answer: D
Carbon forms four covalent bonds in methane.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the usual valency of nitrogen in ammonia, NH3?
A. 1
B. 3
C. 2
D. 4
Correct Answer: B
Nitrogen forms three N−H bonds in ammonia.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the usual valency of oxygen in many compounds?
A. 2
B. 1
C. 4
D. 3
Correct Answer: A
Oxygen commonly forms two bonds or gains two electrons in ionic compounds.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is the usual valency of hydrogen in many compounds?
A. 1
B. 2
C. 3
D. 4
Correct Answer: A
Hydrogen commonly forms one bond.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Valency
What is valency in elementary chemistry?
A. The atomic mass only
B. The number of neutrons only
C. The melting point
D. The combining capacity of an atom
Correct Answer: D
Valency describes how many electrons an atom tends to lose, gain or share in bonding.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Groups & Periods
Lanthanides and actinides are usually displayed in which part of the periodic table?
A. Two rows below the main table
B. Between Groups 17 and 18 only
C. Above hydrogen
D. Inside Group 1 only
Correct Answer: A
The f-block elements are commonly shown separately below to keep the table compact.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Groups & Periods
Which block contains most transition metals?
A. s-block only
B. p-block only
C. d-block
D. f-block only
Correct Answer: C
Transition metals occupy the d-block in the center of the periodic table.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Groups & Periods
The period number of a main-group element broadly corresponds to what?
A. Number of occupied principal electron shells
B. Number of isotopes
C. Atomic mass divided by two
D. Number of neutrons
Correct Answer: A
For main-group elements, period number indicates the highest occupied principal shell.
CSS - PMS - CCE - PCS - General Science
Periodic Table - Groups & Periods
Across a period from left to right, atomic number generally does what?
A. Doubles each step
B. Remains constant
C. Increases by one from element to element
D. Decreases randomly
Correct Answer: C
The periodic table is ordered by increasing atomic number.
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Periodic Table - Groups & Periods
Which group contains the noble gases?
A. Group 18
B. Group 17
C. Group 2
D. Group 16
Correct Answer: A
Group 18 contains the noble gases.
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Periodic Table - Groups & Periods
Which group contains the halogens?
A. Group 14
B. Group 1
C. Group 17
D. Group 18
Correct Answer: C
Fluorine, chlorine, bromine and iodine are halogens in Group 17.