What is the ordinary temperature of the surfaces of metals that are covered with a thin layer of oxide?
(i)Magnesium
(ii)Aluminium
(iii)Zinc
(iv)Oxide etc.,
Options i,ii,iii
Options i,ii,iv
Options ii,iii,iv
All of the Above
The question asks to identify which of the given metals (Magnesium, Aluminium, Zinc) form a thin layer of oxide at ordinary temperatures. This phenomenon is known as passivation, where a protective oxide layer forms on the metal surface, preventing further corrosion.
Based on the above, Magnesium, Aluminium, and Zinc all form a thin layer of oxide on their surfaces at ordinary temperatures.
Correct Option: A) Options i,ii,iii
The question asks to identify a metal that does not burn easily as a bulk piece but burns vigorously when its filings are sprinkled into a flame. This phenomenon is related to the surface area available for reaction and the ignition temperature of the metal.
D) Iron — Iron does not burn easily as a bulk piece, but its filings have a large surface area, allowing them to react rapidly with oxygen in the flame, burning vigorously with sparks.
This question tests knowledge about the reactivity of metals, specifically copper, with atmospheric oxygen when heated. When copper is heated in air, it reacts with oxygen to form an oxide layer. The color of this layer is a key indicator of the product formed.
\[ 2\text{Cu(s)} + \text{O}_2\text{(g)} \xrightarrow{\text{Heat}} 2\text{CuO(s)} \]
Here, \(\text{Cu}\) is copper and \(\text{CuO}\) is copper(II) oxide, which is black.Correct Option: B) Copper(II) Oxide
When copper metal is heated in air, it reacts with atmospheric oxygen to form copper(II) oxide (\(\text{CuO}\)), which is a black-colored compound that coats the surface of the metal.
Which two do not react with oxygen even at high temperatures?
Gold and Platinum
Iron and Copper
Copper and Zinc
Silver and Gold
The question asks to identify two metals that do not react with oxygen even at high temperatures. This property is related to the reactivity series of metals. Metals that are low in the reactivity series are less reactive and tend not to react with oxygen or other common reagents easily, even when heated.
Gold and Platinum are known as noble metals because of their extremely low reactivity. They are found at the very bottom of the reactivity series. Consequently, they do not react with oxygen even at high temperatures. This property makes them highly valuable and resistant to corrosion.
What is the name of the reaction?
Ca(s) + 2H2O(l) → Ca(OH)2 (aq) + H2 (g)
Calcium Reaction
Decomposition Reaction
Synthesis Reaction
Chlorine Reaction
The question asks to identify the type of chemical reaction represented by the given equation: Ca(s) + 2H2O(l) → Ca(OH)2(aq) + H2(g). We need to analyze the reactants and products to classify the reaction.
Correct Option: A) Calcium Reaction. This reaction specifically involves calcium metal reacting with water. While chemically it is a single displacement reaction, among the given choices, "Calcium Reaction" is the most direct description related to the primary reactant.
The question describes a phenomenon where calcium starts floating in a liquid because bubbles stick to its surface. This implies a chemical reaction is occurring that produces a gas, and the buoyancy provided by these gas bubbles causes the metal to float. We need to identify the specific gas produced when calcium reacts with water, as calcium is known to react with water.
D) Hydrogen Gas — As explained in the step-by-step analysis, calcium reacts with water to produce hydrogen gas. These hydrogen gas bubbles stick to the surface of the calcium, making it buoyant enough to float.