Correct Answer: A) Sodium
Explanation: Sodium compounds, particularly sodium salts, are used to produce a bright yellow color in fireworks. Sodium imparts a strong, distinctive yellow color when ignited.
A) Water and carbon monoxide
B) Water and carbon dioxide
C) Carbon dioxide and sulfur dioxide
D) Carbon monoxide and sulfur dioxide
Correct Answer: B) Water and carbon dioxide
Explanation: The complete combustion of hydrocarbons, such as in fossil fuels, typically produces water (H₂O) and carbon dioxide (CO₂) as the main products.
A) Sodium
B) Strontium
C) Barium
D) Copper
Correct Answer: A) Sodium
Explanation: Sodium compounds, particularly sodium salts, are used to produce a bright yellow color in fireworks. Sodium imparts a strong, distinctive yellow color when ignited.
A) Hematite
B) Bauxite
C) Galena
D) Chalcocite
Correct Answer: C) Galena
Explanation: Galena is a mineral primarily composed of lead sulfide () and is the most important ore of lead. It is commonly used for the extraction of lead metal.
A) Iron
B) Platinum
C) Nickel
D) Zinc
Correct Answer: C) Nickel
Explanation: Nickel is widely used as a catalyst in the hydrogenation of unsaturated fats to produce saturated fats, a process commonly employed in the food industry to convert liquid vegetable oils into solid or semi-solid fats.
A) Cellulose
B) Isoprene
C) Starch
D) Ethylene
Correct Answer: B) Isoprene
Explanation: Natural rubber is primarily composed of polyisoprene, which is a polymer of the monomer isoprene. This gives natural rubber its elastic properties.
A) Water
B) Salt
C) Carbon dioxide
D) All of the above
Correct Answer: D) All of the above
Explanation: The reaction between an acid and a metal carbonate typically produces salt, water, and carbon dioxide.
A) To speed up neutrons
B) To slow down neutrons
C) To absorb excess neutrons
D) To generate free neutrons
Correct Answer: B) To slow down neutrons
Explanation: A moderator in a nuclear reactor is used to slow down fast neutrons produced by fission, making them more likely to cause further fission events and sustain a chain reaction.
A) Chromium
B) Manganese
C) Cobalt
D) Molybdenum
Correct Answer: A) Chromium
Explanation: Chromium is added to steel to improve its oxidation resistance at high temperatures. Stainless steel contains chromium, which forms a passive layer of chromium oxide that prevents further corrosion.
A) Amide
B) Alkene
C) Ether
D) Ester
Correct Answer: D) Ester
Explanation: Esters are formed by the reaction of an acid with an alcohol, a process known as esterification. Esters are commonly used as solvents and in the manufacture of plastics and perfumes.
A) Filtration
B) Distillation
C) Centrifugation
D) Electrolysis
Correct Answer: C) Centrifugation
Explanation: Centrifugation is used to separate isotopes of uranium, such as enriching uranium-235 from its more abundant isotope, uranium-238. This process involves spinning uranium hexafluoride gas at high speeds to separate the isotopes based on their masses.
A) Exothermic reaction
B) Endothermic reaction
C) Synthesis reaction
D) Decomposition reaction
Correct Answer: B) Endothermic reaction
Explanation: Endothermic reactions involve the absorption of energy from the surroundings, usually in the form of heat. This absorption of energy is necessary for the reaction to proceed.
A) Metamorphic
B) Sedimentary
C) Igneous
D) Fossiliferous
Correct Answer: C) Igneous
Explanation: Igneous rocks are formed from the cooling and solidification of magma or lava. Examples include basalt and granite, which are commonly found in the Earth’s crust.
A) Boiling point
B) Freezing point
C) Viscosity
D) Transparency
Correct Answer: A) Boiling point
Explanation: When salt is dissolved in water, it causes an elevation in the boiling point of the solution, a phenomenon known as boiling point elevation. This is due to the addition of solute particles which interfere with the evaporation process.
A) Aluminum
B) Copper
C) Gold
D) Silver
Correct Answer: B) Copper
Explanation: Copper is renowned for its excellent thermal and electrical conductivity, which makes it a top choice for electrical wiring and components. It is also highly ductile and can be easily formed into wires.
A) Acetic acid
B) Citric acid
C) Hydrochloric acid
D) Sulfuric acid
Correct Answer: A) Acetic acid
Explanation: Vinegar primarily consists of acetic acid (CH3COOH), which gives it its characteristic sour taste and pungent smell.
A) Red
B) Blue
C) Green
D) Violet
Correct Answer: D) Violet
Explanation: Potassium imparts a characteristic violet color to a flame when it undergoes a flame test, a diagnostic method used to detect the presence of certain elements based on the color of flame they produce.
A) Molar mass
B) Atomic mass
C) Molecular weight
D) Avogadro’s number
Correct Answer: A) Molar mass
Explanation: Molar mass is the term used to describe the mass of one mole of a substance, typically expressed in grams per mole.
A) Hydrogenation
B) Fermentation
C) Esterification
D) Saponification
Correct Answer: A) Hydrogenation
Explanation: Hydrogenation is the process of adding hydrogen to vegetable oils, converting them into solid fats by saturating the carbon-carbon double bonds in the fatty acids.
A) Iron
B) Copper
C) Aluminum
D) Zinc
Correct Answer: C) Aluminum
Explanation: Aluminum is protected by a thin layer of aluminum oxide that forms on the surface when exposed to air. This layer prevents further oxidation and corrosion of the metal beneath.
A) Sodium chloride
B) Calcium carbonate
C) Potassium sulfate
D) Magnesium nitrate
Correct Answer: B) Calcium carbonate
Explanation: Calcium carbonate is a primary contributor to ‘hard’ water and can lead to the buildup of mineral deposits in pipes, boilers, and other appliances.
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