Science Olympiad Test: Metals and Non-Metals- 1 - Free MCQ with solutions

In general, metals are not dull instead they are shiny. Because they contain free electrons that vibrate when they come in contact with light. When the electrons vibrate, they produce their own light. This is reflected to create a shiny look of the metal.
But metals become dull only when they are exposed to the air for a while, the oxygen present in the air slowly combines with the metal to form a metal oxide. It deposits in layers on the surface of the metal which results in the dullness of metals.

Metals are good conductors of electricity. silver is found in pure form from the earth. so  In the given options all are metals. Among them, silver is the best conductor of electricity after second best conductor of electricity is gold.

• Aluminium is ductile and has a high electrical conductivity, which makes it unsuitable for utensil production.
• Aluminium has a high melting point and good heat conductivity.
• Copper, steel, and aluminium are the most popular metals used to make utensils.
• Due to their ability to conduct heat, copper and aluminium are the most used materials.

An electrical fuse is a safety device in the circuit that protects electrical systems by breaking the connection when a short circuit is occurring. The fuse wire is made up of Sn (tin) and Pb (lead) alloy because of its high resistance and low melting. Point. The tin and lead alloy is a eutectic composition consisting of 62% and tin plus 38% lead, which melts at 183⁰C

Explanation:

The reaction between aluminium (Al) and sodium hydroxide (NaOH) produces sodium tetrahydroxoaluminate (NaAl(OH)4) and hydrogen gas (H2). This reaction can be represented as: 

2Al + 2NaOH + 6H₂O → 2NaAl(OH)₄ + 3H₂ 

Why are other options incorrect?

• Oxygen is evolved: 

  Oxygen is not evolved in this reaction. The reaction involves the oxidation of aluminium and the reduction of hydrogen. Oxygen evolution typically occurs in oxidation reactions, such as the decomposition of hydrogen peroxide. 

• Water is produced: 

  Water is a reactant in this reaction, not a product. It is used to facilitate the dissolution of aluminium and provide the necessary oxygen atoms for the formation of sodium tetrahydroxoaluminate. 

• No reaction takes place: 

  This is incorrect. Aluminium reacts readily with sodium hydroxide. The reaction is quite visible due to the evolution of hydrogen gas. 

An amphoteric oxide is a substance that can chemically react as either acid or base. Aluminium oxide shows acid and basic properties of oxide so it is amphoteric.
Thus, Al₂​O_3​ entails the marking point at which a change over from a basic oxide to acidic oxide occurs.

Caratage is the measurement of purity of gold alloyed with other metals. 24 carat is pure gold with no other metals. Low caratages contain less gold. 18 carat gold contain 75% of gold & 25% of other metals often, Copper/Silk.

Fe does not react with cold as well as hot water. It reacts only with steam.

Because silver is a non-reactive metal it can be displaced easily.

• Mg, Zn, or Cu metals would displace Ag from the solution of its salt.
• The standard reduction potential for the half reaction Ag is the highest among the metals.
• As a result, Ag⁺ ion has the greatest strength as an oxidising agent among the metals (ions).
• The Ag + ion gains an electron while other metals loses.

The chemical equation for the reaction of iron with steam can be written as
3Fe(s) + 4H₂O → Fe₃O₄ + H₂
Iron + Water → Iron (II, III) oxide + hydrogen gas
The formation of iron(II, III) oxide and hydrogen when red hot iron interacts with steam. When an iron metal interacts with steam, metal oxide and hydrogen gas are the products that are produced.