Metals, Non-Metals, and Reactivity Order of Metals
Metals, Non-Metals, and Reactivity Order of Metals MCQ Questions
1.
Which of the following correctly defines 'malleability' as a property of metals?
A.
The ability of a metal to conduct heat efficiently
B.
The ability of a metal to be beaten/hammered into thin sheets
C.
The ability of a metal to produce a ringing sound when struck
D.
The ability of a metal to be drawn into thin wires
ANSWER :
B. The ability of a metal to be beaten/hammered into thin sheets
Approach
The question asks for the correct definition of 'malleability' as a property of metals. We need to recall the definitions of various physical properties of metals to identify the correct one.
Step-by-step
- Understand the term 'malleability': Malleability is a physical property of metals that describes their ability to deform under compressive stress. This means they can be hammered or rolled into thin sheets without breaking.
- Evaluate Option A: "The ability of a metal to conduct heat efficiently" refers to thermal conductivity, not malleability.
- Evaluate Option B: "The ability of a metal to be beaten/hammered into thin sheets" perfectly matches the definition of malleability. Gold and silver are excellent examples of malleable metals.
- Evaluate Option C: "The ability of a metal to produce a ringing sound when struck" refers to sonority (or sonorousness), which is another characteristic property of metals, but not malleability.
- Evaluate Option D: "The ability of a metal to be drawn into thin wires" refers to ductility, which is distinct from malleability. While many metals are both malleable and ductile, these are different properties.
Correct Option:
B) The ability of a metal to be beaten/hammered into thin sheets. This is the precise definition of malleability. Metals like gold, silver, and aluminum are highly malleable.
Incorrect Options
- A) The ability of a metal to conduct heat efficiently — This property is known as thermal conductivity.
- C) The ability of a metal to produce a ringing sound when struck — This property is known as sonority or sonorousness.
- D) The ability of a metal to be drawn into thin wires — This property is known as ductility.
2.
The property of metals that allows them to be drawn into thin wires is known as:
Approach
The question asks for the specific property of metals that allows them to be drawn into thin wires. This requires knowledge of the physical properties of metals.
Step-by-step
- Recall the common physical properties of metals. These include malleability, ductility, lustre, sonority, good conductivity of heat and electricity, and high melting/boiling points.
- Consider the definition of each property mentioned in the options in relation to the ability to be drawn into wires.
- Ductility: This is the ability of a material to be stretched into a thin wire without breaking. Metals like copper, gold, and aluminum are highly ductile.
- Malleability: This is the ability of a material to be hammered or rolled into thin sheets without breaking.
- Lustre: This refers to the shiny appearance of metals.
- Sonority: This is the property of metals to produce a ringing sound when struck.
- Based on these definitions, the property directly related to being drawn into thin wires is ductility.
Correct Option: D) Ductility — Ductility is the physical property of a material that describes its ability to be drawn into a thin wire. This is a characteristic feature of many metals, such as copper, gold, and aluminum, which are commonly used to make wires.
Incorrect Options
- A) Malleability — Malleability is the property of a material to be hammered or rolled into thin sheets without breaking. While many metals are both malleable and ductile, malleability specifically refers to forming sheets, not wires.
- B) Lustre — Lustre refers to the shiny appearance of a metal. It is a surface property and has no relation to the ability to be drawn into wires.
- C) Sonority — Sonority is the property of a material to produce a ringing sound when struck. This property is related to the sound-producing capability of metals, not their ability to be formed into wires.
3.
Which metal is known to be the best conductor of electricity among all metals?
Approach
The question asks to identify the best conductor of electricity among the given options. Electrical conductivity in metals is primarily determined by the availability of free electrons and their mobility. We need to compare the conductivity of the listed metals.
Step-by-step
- Understanding Electrical Conductivity: Electrical conductivity is a measure of a material's ability to conduct an electric current. It is the reciprocal of electrical resistivity. Materials with high conductivity have low resistivity.
- Factors Affecting Conductivity: The conductivity of a metal depends on the number of free electrons per unit volume and the ease with which these electrons can move through the material (i.e., their mobility).
- Comparing Metals: We need to recall the relative conductivities of common metals. Generally, metals like silver, copper, and gold are excellent conductors due to their atomic structure, which allows for a 'sea' of delocalized electrons.
- Ranking of Common Conductors: Among common metals, silver is known to have the highest electrical conductivity at room temperature. Copper is very close to silver in conductivity and is widely used due to its lower cost. Gold is also an excellent conductor but is less conductive than silver and copper, and much more expensive. Aluminium is a good conductor, but significantly less conductive than silver, copper, or gold.
Correct Option:
C) Silver is known to be the best conductor of electricity among all metals, possessing the highest electrical conductivity at standard temperatures.
Incorrect Options
- A) Aluminium is a good conductor of electricity and is widely used in power transmission lines due to its lower density and cost compared to copper. However, its conductivity is lower than that of silver, copper, and gold.
- B) Gold is an excellent conductor of electricity and is highly resistant to corrosion, making it valuable for electrical contacts in high-reliability applications. However, its electrical conductivity is less than that of silver and copper.
- D) Copper is an excellent conductor of electricity, second only to silver in terms of conductivity among common metals. It is widely used in electrical wiring and many electronic devices due to its high conductivity and relatively lower cost compared to silver.
4.
Which of the following metals exists in a liquid state at normal room temperature?
Approach
The question asks to identify which of the given metals is in a liquid state at normal room temperature. This requires knowledge of the physical properties, specifically the melting points, of common metals.
Step-by-step
- Recall the typical state of metals at room temperature. Most metals are solid at room temperature.
- Consider the options provided and their known melting points.
- Mercury (Hg): Mercury is famously known for its low melting point, which is approximately \(-38.83^\circ \text{C}\) (\(234.32 \, \text{K}\)). This means it is liquid at normal room temperature, which is typically considered to be around \(20-25^\circ \text{C}\).
- Potassium (K): Potassium is an alkali metal with a melting point of about \(63.5^\circ \text{C}\). It is a soft solid at room temperature.
- Sodium (Na): Sodium is another alkali metal with a melting point of about \(97.8^\circ \text{C}\). It is also a soft solid at room temperature.
- Lithium (Li): Lithium is an alkali metal with a melting point of about \(180.5^\circ \text{C}\). It is a solid at room temperature.
- Based on these melting points, only mercury exists in a liquid state at normal room temperature.
Correct Option:
B) Mercury is the only metal among the given options that exists in a liquid state at normal room temperature (around \(20-25^\circ \text{C}\)). Its melting point is well below this range, at approximately \(-38.83^\circ \text{C}\).
Incorrect Options
- A) Potassium — Potassium has a melting point of about \(63.5^\circ \text{C}\), which means it is a solid at normal room temperature.
- C) Sodium — Sodium has a melting point of about \(97.8^\circ \text{C}\), making it a solid at normal room temperature.
- D) Lithium — Lithium has a melting point of about \(180.5^\circ \text{C}\), and thus it is a solid at normal room temperature.
5.
Which of the following is a non-metal that exists as a liquid at room temperature?
Approach
The question asks to identify a non-metal that exists in a liquid state at room temperature. This requires knowledge of the physical properties of common non-metals, particularly their states of matter at standard conditions.
Step-by-step
- Recall the general properties of non-metals. Non-metals typically exist as solids or gases at room temperature.
- Consider the options provided and their states at room temperature (approximately \(20^\circ\text{C}\) to \(25^\circ\text{C}\)).
- Sulphur: Sulphur is a yellow solid at room temperature.
- Bromine: Bromine is a reddish-brown liquid at room temperature. It is the only non-metallic element that is liquid at room temperature.
- Phosphorus: Phosphorus exists in several allotropic forms, but the most common ones (white and red phosphorus) are solids at room temperature.
- Iodine: Iodine is a lustrous, purplish-black solid at room temperature that readily sublimes to form a violet gas.
- Based on this, Bromine is the correct answer as it is a non-metal and exists as a liquid at room temperature.
Correct Option: B) Bromine is a non-metal that exists as a reddish-brown liquid at room temperature. It is unique among non-metals in this regard.
Incorrect Options
- A) Sulphur — Sulphur is a yellow solid at room temperature.
- C) Phosphorus — Phosphorus (e.g., white or red phosphorus) is a solid at room temperature.
- D) Iodine — Iodine is a purplish-black solid at room temperature.
6.
The property of metals due to which they produce a ringing sound when struck is called:
Approach
The question asks for the specific property of metals that causes them to produce a ringing sound when struck. We need to identify the correct term from the given options that describes this characteristic.
Step-by-step
- Consider the properties listed in the options. Each option describes a distinct physical property of materials, particularly metals.
- Ductility refers to the ability of a material to be drawn into thin wires. This is not related to sound production.
- Malleability refers to the ability of a material to be hammered or pressed into thin sheets without breaking. This is also not related to sound production.
- Sonority is the property of a material to produce a deep, clear, resonant sound when struck. This perfectly matches the description in the question.
- Lustre refers to the shiny appearance of a material. This is a visual property, not an auditory one.
- Based on these definitions, 'Sonority' is the correct property.
Correct Option: C) Sonority is the property of materials, especially metals, to produce a ringing sound when struck. This is why bells are made of metal, and why metals are often used in musical instruments.
Incorrect Options
- A) Ductility — This is the ability of a material to be drawn into thin wires. It has no relation to sound production.
- B) Malleability — This is the ability of a material to be hammered or pressed into thin sheets. It is not related to producing a ringing sound.
- D) Lustre — This refers to the shiny appearance of a material, which is a visual property and not related to sound.
