1: What is the atomic number of calcium?
A: 18
B: 19
C: 20
D: 21
Correct Answer: C
Explanation: The atomic number of calcium is 20, indicating it has 20 protons in its nucleus.
2: Who first isolated pure calcium?
A: Antoine Lavoisier
B: Joseph Black
C: Humphry Davy
D: Jöns Jakob Berzelius
Correct Answer: C
Explanation: Humphry Davy first isolated pure calcium in 1808 via electrolysis of its oxide.
3: What is the most common calcium compound found on Earth?
A: Calcium sulfate
B: Calcium fluoride
C: Calcium carbonate
D: Calcium nitrate
Correct Answer: C
Explanation: The most common calcium compound on Earth is calcium carbonate, which is found in limestone.
4: What is the symbol for calcium on the periodic table?
A: Ca
B: C
C: Cl
D: Cs
Correct Answer: A
Explanation: The symbol for calcium on the periodic table is Ca.
5: At what temperature does calcium metal melt?
A: 842°C
B: 1000°C
C: 1494°C
D: 1548°C
Correct Answer: A
Explanation: Calcium metal melts at 842°C.
6: In which crystal structure does calcium crystallize at room temperature?
A: Body-centered cubic
B: Face-centered cubic
C: Hexagonal close-packed
D: Simple cubic
Correct Answer: B
Explanation: Calcium crystallizes in the face-centered cubic arrangement at room temperature.
7: Which of the following is NOT a common source of calcium?
A: Dolomite
B: Limestone
C: Diamond
D: Gypsum
Correct Answer: C
Explanation: Diamond is an allotrope of carbon and not a common source of calcium.
8: What percentage of natural calcium is the isotope 40Ca?
A: 99.9%
B: 96.9%
C: 50.0%
D: 2.5%
Correct Answer: B
Explanation: The isotope 40Ca makes up 96.9% of all natural calcium.
9: How many electrons are there in a calcium atom?
A: 18
B: 19
C: 20
D: 21
Correct Answer: C
Explanation: A calcium atom has 20 electrons.
10: What is the electronegativity of calcium on the Pauling scale?
A: 0.98
B: 1.00
C: 1.50
D: 2.00
Correct Answer: B
Explanation: The electronegativity of calcium on the Pauling scale is 1.00.
11: Which calcium ion plays a vital role in signal transduction pathways and muscle contraction?
A: Ca+
B: Ca-
C: Ca2+
D: Ca3+
Correct Answer: C
Explanation: The calcium ion Ca2+ plays a vital role in physiological and biochemical processes such as signal transduction pathways and muscle contraction.
12: What color does calcium typically appear to be?
A: Dull gray, silver with a pale yellow tint
B: Shiny black
C: Golden brown
D: Bright red
Correct Answer: A
Explanation: Calcium appears dull gray, silver with a pale yellow tint.
13: What is the primary reason that pure calcium metal has few applications?
A: It is too expensive.
B: It is highly reactive.
C: It is too rare.
D: It is non-conductive.
Correct Answer: B
Explanation: Pure calcium metal has few applications due to its high reactivity.
14: Calcium ions are important for maintaining which physiological feature?
A: Blood sugar levels
B: Potential difference across cell membranes
C: Oxygen levels in blood
D: Body temperature
Correct Answer: B
Explanation: Calcium ions are important for maintaining the potential difference across excitable cell membranes.
15: Which historical figure suggested lime might be an oxide of a fundamental chemical element?
A: Joseph Black
B: Antoine Lavoisier
C: Humphry Davy
D: Jöns Jakob Berzelius
Correct Answer: B
Explanation: Antoine Lavoisier suggested that lime might be an oxide of a fundamental chemical element in 1789.
16: What is the primary use of metallic calcium in industry?
A: Jewellery making
B: Insulation
C: Steelmaking
D: Plastic manufacture
Correct Answer: C
Explanation: The largest use of metallic calcium is in steelmaking.
17: Which food is a rich source of calcium?
A: Beef
B: Bananas
C: Kale
D: Potatoes
Correct Answer: C
Explanation: Kale is a food rich in calcium.
18: What does the term “alkaline earth metal” refer to in the periodic table?
A: A group of metals that are very heavy
B: A group of elements with one valence electron
C: A group of metals in Group 2
D: A group of non-metals
Correct Answer: C
Explanation: “Alkaline earth metal” refers to metals in Group 2 of the periodic table.
19: What is the CAS Number for calcium?
A: 7440-70-2
B: 7704-34-9
C: 1309-37-1
D: 7446-09-5
Correct Answer: A
Explanation: The CAS Number for calcium is 7440-70-2.
20: What are the most common forms of calcium carbonate?
A: Limestone and chalk
B: Granite and basalt
C: Diamond and sapphire
D: Quartz and feldspar
Correct Answer: A
Explanation: The most common forms of calcium carbonate are limestone and chalk.
21: Which element is a close homolog to calcium?
A: Iron
B: Strontium
C: Lithium
D: Helium
Correct Answer: B
Explanation: Calcium’s physical and chemical properties are most similar to strontium.
22: What is the primary reaction of calcium with water?
A: It forms calcium nitrate.
B: It produces calcium hydroxide and hydrogen gas.
C: It forms calcium phosphate.
D: It decomposes to carbon dioxide.
Correct Answer: B
Explanation: Calcium reacts with water to produce calcium hydroxide and hydrogen gas.
23: What is the boiling point of calcium?
A: 1115 K
B: 1200 K
C: 1494 K
D: 1757 K
Correct Answer: D
Explanation: The boiling point of calcium is 1757 K.
24: Calcium’s role in neurotransmitter release occurs in:
A: Muscles
B: Kidneys
C: Neurons
D: Bones
Correct Answer: C
Explanation: Calcium ions play a vital role in neurotransmitter release from neurons.
25: What historical use of lime dates back to around 7000 BC?
A: Building material
B: Currency
C: Medicine
D: Cooking
Correct Answer: A
Explanation: Lime was used as a building material as far back as around 7000 BC.
26: What does the calcium ion Ca2+ regulate in muscles?
A: Energy production
B: Contraction
C: Oxygen supply
D: Waste removal
Correct Answer: B
Explanation: Calcium ion Ca2+ regulates the contraction of muscles.
27: Which state is calcium most commonly found in at standard temperature and pressure (STP)?
A: Gas
B: Liquid
C: Plasma
D: Solid
Correct Answer: D
Explanation: At standard temperature and pressure, calcium is found in a solid phase.
28: How many stable isotopes does natural calcium have?
A: 3
B: 4
C: 5
D: 6
Correct Answer: C
Explanation: Natural calcium has five stable isotopes: 40Ca, 42Ca, 43Ca, 44Ca, and 46Ca.
29: Which isotopic form of calcium has the longest half-life?
A: 41Ca
B: 43Ca
C: 45Ca
D: 48Ca
Correct Answer: D
Explanation: 48Ca has a half-life of about 4.3 × 1019 years, thus effectively stable.
30: How does calcium primarily react with oxygen?
A: Forms calcium sulfide
B: Forms calcium hydroxide
C: Forms calcium oxide
D: Forms calcium chloride
Correct Answer: C
Explanation: Calcium primarily reacts with oxygen to form calcium oxide.
31: Which category does calcium belong to in the periodic table?
A: Halogens
B: Noble gases
C: Alkaline earth metals
D: Transition metals
Correct Answer: C
Explanation: Calcium belongs to the alkaline earth metals in Group 2 of the periodic table.
32: In what type of reactions does calcium typically lose its valence electrons?
A: Oxidation
B: Neutralization
C: Precipitation
D: Reductions
Correct Answer: A
Explanation: Calcium typically loses its valence electrons in oxidation reactions to form a Ca2+ cation.
33: Natural water hardness is often characterized by what element?
A: Magnesium
B: Sodium
C: Calcium
D: Potassium
Correct Answer: C
Explanation: Natural water hardness is often characterized by the concentration of calcium ions.
34: What device uses calcium as an alloy to reduce self-discharging?
A: Solar panels
B: Wind turbines
C: Automotive batteries
D: LED lights
Correct Answer: C
Explanation: Calcium is used as an alloy in maintenance-free automotive batteries to reduce self-discharging.
35: How is calcium produced in the United States and Canada?
A: By reducing lime with aluminum at high temperatures
B: By heating calcium carbonate
C: By using hydroelectric power
D: By natural decomposition
Correct Answer: A
Explanation: In the United States and Canada, calcium is produced by reducing lime with aluminum at high temperatures.
36: Which mineral is primarily responsible for the calcium cycle’s link between tectonics, climate, and the carbon cycle?
A: Pyrite
B: Calcite
C: Feldspar
D: Diamond
Correct Answer: B
Explanation: Calcite, a form of calcium carbonate, plays a significant role in the calcium cycle’s link between tectonics, climate, and the carbon cycle.
37: What is the density of calcium metal at 20°C?
A: 0.9 g/cm³
B: 1.0 g/cm³
C: 1.526 g/cm³
D: 2.0 g/cm³
Correct Answer: C
Explanation: The density of calcium metal at 20°C is 1.526 g/cm³.
38: Which method is used to distinguish between calcium isotopes in geological applications?
A: Colorimetric analysis
B: Mass spectroscopy
C: X-ray diffraction
D: Ultraviolet spectroscopy
Correct Answer: B
Explanation: Mass spectroscopy is used to distinguish between calcium isotopes in geological applications.
39: What industry uses calcium compounds as bleaching agents?
A: Textile
B: Paper
C: Plastic
D: Automotive
Correct Answer: B
Explanation: The paper industry uses calcium compounds as bleaching agents.
40: What is the role of calcium ions in blood clotting?
A: To transport oxygen
B: To break down glucose
C: To aid in collagen formation
D: To facilitate the coagulation process
Correct Answer: D
Explanation: Calcium ions play a crucial role in facilitating the coagulation process in blood clotting.
41: Which compound is used in cement and electrical insulators?
A: Calcium chloride
B: Calcium nitrate
C: Calcium carbonate
D: Calcium sulfate
Correct Answer: C
Explanation: Calcium compounds such as calcium carbonate are used in cement and electrical insulators.
42: What role do calcium ions play in bone formation?
A: As a structural framework
B: As cofactors in metabolic pathways
C: As second messengers
D: In signal transduction
Correct Answer: A
Explanation: Calcium ions play a vital role in bone formation as a structural framework.
43: What natural occurrence form does calcium primarily derive from?
A: Metamorphic
B: Igneous
C: Sedimentary
D: Primordial
Correct Answer: D
Explanation: Calcium primarily occurs in its primordial form.
44: What is calcium iodide used for in the food industry?
A: As a flavor enhancer
B: As an antioxidant
C: As a bleaching agent
D: As a preservative
Correct Answer: C
Explanation: Calcium iodide is used as a bleaching agent in the food industry.
45: Which of the following is a secondary messenger role played by calcium ions in cells?
A: DNA replication
B: Bone formation
C: Signal transduction
D: Muscle relaxation
Correct Answer: C
Explanation: Calcium ions play a secondary messenger role in signal transduction pathways within cells.
46: Calcium ions contribute to maintaining which key physiological process?
A: Blood glucose levels
B: Blood clotting
C: Oxygen transport
D: Waste elimination
Correct Answer: B
Explanation: Calcium ions contribute significantly to blood clotting.
47: What is the chemical formula of calcium carbonate?
A: CaO
B: CaCO3
C: CaCl2
D: Ca(OH)2
Correct Answer: B
Explanation: The chemical formula of calcium carbonate is CaCO3.
48: Which isotope of calcium is used in studying metabolic bone disease?
A: 40Ca
B: 42Ca
C: 44Ca
D: 48Ca
Correct Answer: C
Explanation: The isotope 44Ca is used in studying metabolic bone diseases like osteoporosis.
49: Which body part derives significant structural support from calcium ions?
A: Skin
B: Eyes
C: Bones
D: Lungs
Correct Answer: C
Explanation: Bones derive significant structural support from calcium ions.
50: Which mythical region is famous for its calcium-rich travertine terraces?
A: Atlantis
B: Pamukkale
C: Shangri-La
D: El Dorado
Correct Answer: B
Explanation: Pamukkale in Turkey is famous for its calcium-rich travertine terraces.
51: What is the primary consequence of calcium deficiency?
A: Hyperactivity
B: Osteoporosis
C: Muscle hypertrophy
D: Respiratory issues
Correct Answer: B
Explanation: The primary consequence of calcium deficiency is osteoporosis.
52: Which calcium compound is commonly used in toothpaste as a polishing agent?
A: Calcium chloride
B: Calcium carbonate
C: Tricalcium phosphate
D: Calcium sulfite
Correct Answer: C
Explanation: Tricalcium phosphate is commonly used in toothpaste as a polishing agent.
53: What is the most common isotope of calcium with a natural abundance of 96.941%?
A: 42Ca
B: 43Ca
C: 40Ca
D: 44Ca
Correct Answer: C
Explanation: The isotope 40Ca has a natural abundance of 96.941%.
54: How does calcium assist in the fertilization process?
A: As a nutrient source
B: By providing energy
C: By acting as a secondary messenger
D: By aiding in genetic replication
Correct Answer: C
Explanation: Calcium ions act as a secondary messenger in the fertilization process.
55: Which alkaline earth metal is biologically very similar to calcium?
A: Magnesium
B: Strontium
C: Barium
D: Radium
Correct Answer: A
Explanation: Biologically, magnesium is very similar to calcium.
56: What does exposure to air do to calcium metal?
A: Makes it shiny
B: Forms a dark oxide-nitride layer
C: Turns it red
D: Makes it brittle
Correct Answer: B
Explanation: Calcium metal forms a dark oxide-nitride layer when exposed to air.
57: Which sea is home to aragonite beds, a source of calcium carbonate?
A: Mediterranean Sea
B: Red Sea
C: Caspian Sea
D: Baltic Sea
Correct Answer: B
Explanation: Aragonite beds, a source of calcium carbonate, are found in the Red Sea basins.
58: What type of materials predominantly contain calcium phosphate?
A: Plaster
B: Ceramics
C: Limestone
D: Bones
Correct Answer: D
Explanation: Bones predominantly contain calcium phosphate in the form of hydroxyapatite.
59: Which global organization lists calcium as an essential medicine?
A: Red Cross
B: UNICEF
C: World Health Organization
D: Doctors Without Borders
Correct Answer: C
Explanation: The World Health Organization lists calcium as an essential medicine.
60: What is the Pauling electronegativity value of calcium?
A: 0.98
B: 1.2
C: 1.00
D: 1.5
Correct Answer: C
Explanation: The Pauling electronegativity value of calcium is 1.00.
Disclaimer: Please consult a physician before making any changes to your health regimen.