NMMS - National Means-cum-Merit Scholarship Science: Metals and Non-Metals Questions and Answers — Questions and Answers
Question 1: A student places a piece of zinc metal into a blue solution of copper sulfate. After some time, the student observes that the blue color of the solution fades and a reddish-brown coating forms on the zinc strip. Which of the following statements best explains this observation?
- Zinc is more reactive than copper and displaces it from the copper sulfate solution. (Correct answer)
- Copper is more reactive than zinc and displaces it from the zinc strip.
- A double displacement reaction occurs, forming zinc sulfate and copper.
- The zinc metal dissolves in the solution without any chemical reaction.
Correct answer: Zinc is more reactive than copper and displaces it from the copper sulfate solution.
This is a classic example of a single displacement reaction. The reactivity series of metals shows that zinc is more reactive than copper. Therefore, zinc can displace copper from its salt solution (copper sulfate). The zinc atoms lose electrons to become zinc ions (which are colorless in solution), and the copper ions in the solution gain electrons to become solid copper metal, which appears as a reddish-brown coating.
Question 2: Most metals are solid at room temperature, hard, and good conductors of electricity. Which of the following pairs represents an exception to these typical metallic properties?
- Iron and Aluminum
- Copper and Silver
- Sodium and Mercury (Correct answer)
- Gold and Platinum
Correct answer: Sodium and Mercury
While most metals are hard solids, sodium is a soft metal that can be easily cut with a knife. Mercury is unique as it is the only metal that is liquid at room temperature. Both are exceptions to the general physical properties of metals.
Question 3: Which of the following non-metals is essential for the process of respiration and is also used in combustion?
- Nitrogen
- Sulfur
- Carbon
- Oxygen (Correct answer)
Correct answer: Oxygen
Oxygen is a non-metal that is vital for aerobic respiration in most living organisms. It is also a key reactant in combustion (burning) processes. While nitrogen is abundant in the air and carbon is the basis of life, oxygen is directly involved in both respiration and combustion.
Question 4: A school bell is made of a metal alloy rather than wood because metals possess a specific property. Which property of metals is primarily responsible for the ringing sound produced by the bell?
- Ductility
- Malleability
- Lustre
- Sonority (Correct answer)
Correct answer: Sonority
Sonority is the property of metals that causes them to produce a ringing sound when struck. This makes them ideal for making bells and musical instruments. Ductility is the ability to be drawn into wires, malleability is the ability to be beaten into sheets, and lustre refers to their shiny appearance.
Question 5: An electrician is choosing a material for the core of an electrical wire. Which property is most crucial for this application, and which material is a suitable choice?
- Low density; Sulfur
- High electrical conductivity; Copper (Correct answer)
- Brittleness; Carbon
- High melting point; Phosphorus
Correct answer: High electrical conductivity; Copper
Electrical wires need to conduct electricity efficiently with minimal loss of energy. Therefore, high electrical conductivity is the most important property. Metals like copper and aluminum are excellent electrical conductors and are widely used for wiring. Non-metals like sulfur, carbon, and phosphorus are poor conductors (insulators).
Question 6: When non-metals react with oxygen, they generally form oxides. What is the typical nature of these non-metallic oxides when dissolved in water?
- Neutral
- Basic
- Acidic (Correct answer)
- Amphoteric
Correct answer: Acidic
Oxides of non-metals are generally acidic in nature. When they dissolve in water, they form acids. For example, sulfur dioxide (SO2), a non-metallic oxide, reacts with water to form sulfurous acid (H2SO3). In contrast, oxides of metals are typically basic.
NMMS - National Means-cum-Merit Scholarship Science: Metals and Non-Metals Questions and Answers
A student places a piece of zinc metal into a blue solution of copper sulfate.
After some time, the student observes that the blue color of the solution fades and a reddish-brown coating forms on the zinc strip.
Which of the following statements best explains this observation?