Chemical Reactions — Set 1
Chemistry · रासायनिक अभिक्रियाएं · Questions 1–10 of 40
What type of chemical reaction occurs when two or more substances combine to form a single new substance?
Correct Answer: C. Combination reaction
• **Combination reaction** = A combination reaction involves multiple reactants joining to create one product. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Displacement reaction; B: Double displacement reaction; D: Decomposition reaction
Which of the following is an example of an exothermic reaction?
Correct Answer: C. Respiration
• **Respiration** = Respiration is an exothermic process because it releases energy for the body's use. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Evaporation of water; B: Melting of ice; D: Photosynthesis
What is the term for a reaction where a more reactive element takes the place of a less reactive element in a compound?
Correct Answer: B. Displacement reaction
• **Displacement reaction** = In a displacement reaction, a highly reactive metal replaces a lower reactivity metal from its salt solution. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Addition reaction; C: Neutralization reaction; D: Redox reaction
In a redox reaction, what happens to the substance that undergoes reduction?
Correct Answer: D. It gains electrons
• **It gains electrons** = Reduction is defined as the gain of electrons by a chemical species. • **oxidation** — Conversely, oxidation involves the loss of electrons during the reaction • 💡 Wrong-option analysis: A: It increases in mass; B: It loses electrons; C: It gains oxygen
What gas is evolved when a dilute acid reacts with a metal like Zinc?
Correct Answer: C. Hydrogen
• **Hydrogen** = Metals react with dilute acids to produce a salt and hydrogen gas. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Oxygen; B: Nitrogen; D: Carbon dioxide
Which chemical is commonly used to test for the presence of Carbon Dioxide gas?
Correct Answer: D. Lime water
• **Lime water** = Lime water turns milky when carbon dioxide gas is passed through it. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Potassium permanganate; B: Litmus solution; C: Iodine solution
The process of food getting spoiled due to oxidation of fats and oils is called?
Correct Answer: A. Rancidity
• **Rancidity** = Rancidity refers to the unpleasant smell and taste in food caused by fat oxidation. • **oxidation** — Rancidity refers to the unpleasant smell and taste in food caused by fat oxid... • 💡 Wrong-option analysis: B: Corrosion; C: Reduction; D: Fermentation
What color change is observed when Lead Nitrate powder is heated strongly?
Correct Answer: B. Turns yellow
• **Turns yellow** = Lead nitrate decomposes upon heating to form lead oxide, which is yellow in color. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Turns blue; C: Turns green; D: Turns pink
Which of these is a physical change rather than a chemical reaction?
Correct Answer: D. Sublimation of camphor
• **Sublimation of camphor** = Sublimation is a physical change because the chemical identity of the substance remains the same. • (Contextual detail from explanation) • 💡 Wrong-option analysis: A: Rusting of iron; B: Burning of paper; C: Digestion of food
What type of reaction occurs when an acid and a base react to form salt and water?
Correct Answer: A. Neutralization
• **Neutralization** = Neutralization is the specific name for the reaction between an acid and a base. • (Contextual detail from explanation) • 💡 Wrong-option analysis: B: Decomposition; C: Hydrogenation; D: Precipitation