Metals And Non-metals - Class 10 MCQ

Bromine is the only non-metal which exists as a liquid at room temperature.

In the neutral atom of an element,

 Bauxite is a commercial ore of aluminium which consists largely of hydrated aluminium oxide, Al₂O₃.2H₂O. 

The process of heating the sulphide ore strongly in the presence of air to convert it into metal oxide, is known as roasting.

In electrolytic refining of a metal, the cathode is made up of pure metal whereas the anode is made up of impure metal.

Aluminium oxide is amphoteric in nature, i.e., it reacts with acids as well as bases to form salt and water.

The decreasing order of the reactivity of the common metals is given below:
  Li, K, Na, Ba, Ca, Mg , Al, Mn, Zn, Fe, Ni, Sn, Pb, [H], Cu,Hg, Ag, Au,Pt 

Explanation:
Given electronic configurations of the elements X, Y, and Z are:
X = 2, 4
Y = 2, 7
Z = 2, 1
Ionic compounds are formed when atoms gain or lose electrons to achieve a stable electron configuration. The elements X, Y, and Z will combine to form an ionic compound based on their electron configurations.
To determine the correct formula, we need to consider the following:
1. X has 2 valence electrons, so it tends to lose 2 electrons to achieve a stable configuration. It will form a cation with a charge of +2.
2. Y has 2 valence electrons and needs to gain 1 electron to achieve a stable configuration. It will form an anion with a charge of -1.
3. Z has 2 valence electrons and needs to gain 6 electrons to achieve a stable configuration. It will form an anion with a charge of -6.
Based on the charges of the ions formed by X, Y, and Z, we can determine the correct formula for the ionic compound:
- The cation X with a charge of +2 can combine with two anions Z with a charge of -6 to form a neutral compound. The formula for this compound is XZ₂.
- The anion Y with a charge of -1 can combine with one cation Z with a charge of +2 to form a neutral compound. The formula for this compound is YZ.
Therefore, the correct formula for the ionic compound formed by X, Y, and Z is YZ.

Z is an ionic compound. It has a high melting point.

The reaction given is: ZnO + CO -> Zn + CO2
To determine which statements about the reaction are correct, we need to analyze the oxidation states of each element involved.
Step 1: Assign oxidation states to each element in the reaction:
- In ZnO, oxygen (O) typically has an oxidation state of -2 and since there is only one oxygen atom, the oxidation state of zinc (Zn) must be +2.
- In CO, oxygen (O) typically has an oxidation state of -2 and carbon (C) typically has an oxidation state of +2, so the oxidation state of carbon (C) in CO is -2.
- In Zn, the overall charge of the compound is 0, so the oxidation state of zinc (Zn) is 0.
- In CO2, oxygen (O) typically has an oxidation state of -2 and since there are two oxygen atoms, the oxidation state of carbon (C) must be +4.
Step 2: Determine the changes in oxidation states:
- The oxidation state of Zn changes from +2 in ZnO to 0 in Zn, which means ZnO is being reduced.
- The oxidation state of C changes from -2 in CO to +4 in CO2, which means CO is being oxidized.
Therefore, the correct statements about the reaction are:
- ZnO is being reduced (ZnO -> Zn)
- CO is being oxidized (CO -> CO2)
Answer: D