Grade 10 : Science - 3. Metals/Non-Metals (Set 3) | Concept of Maths

Question 1

Ananya is testing three unknown metals $M_1$, $M_2$, and $M_3$. She records the following observations:
• $M_1$ reacts violently with cold water, and the evolved gas catches fire immediately.
• $M_2$ does not react with cold water but reacts readily with hot water, causing the metal to float.
• $M_3$ does not react with hot or cold water but reacts only with steam.
Which of the following correctly identifies $M_1$, $M_2$, and $M_3$?

Accepted Answer

B) $M_1 = K$, $M_2 = Mg$, $M_3 = Fe$

Answer

A) $M_1 = Na$, $M_2 = Fe$, $M_3 = Mg$

Answer

C) $M_1 = Mg$, $M_2 = Ca$, $M_3 = Zn$

Answer

D) $M_1 = Ca$, $M_2 = Na$, $M_3 = Fe$

Question 2

An ionic compound $XY_2$ is formed when metal X (atomic number 12) combines with non-metal Y (atomic number 17). Which of the following statements is incorrect regarding the compound $XY_2$?

Accepted Answer

B) It conducts electricity in the solid state.

Answer

A) It has a high melting and boiling point.

Answer

C) It is generally soluble in polar solvents like water.

Answer

D) It is formed by the complete transfer of electrons from X to Y.

Question 3

A student was asked to write the extraction steps for obtaining pure zinc from zinc blende (ZnS) and calamine ($ZnCO_3$). The student wrote the following chemical equations:
$$Reaction A: 2ZnS + 3O_2 \xrightarrow{\Delta} 2ZnO + 2SO_2$$
$$Reaction B: ZnCO_3 \xrightarrow{\Delta} ZnO + CO_2$$
The student labeled both processes as "Roasting". Identify the error in the student's classification.

Accepted Answer

C) Reaction A is Roasting, while Reaction B is Calcination.

Answer

A) Reaction A is Calcination, and Reaction B is Roasting.

Answer

B) Both reactions are Calcination processes.

Answer

D) Both reactions are Roasting, but Reaction B requires excess oxygen.

Question 4

Aluminum oxide ($Al_2O_3$) is treated as an amphoteric oxide because it reacts with both acids and bases. If 1 mol of $Al_2O_3$ reacts completely with sodium hydroxide (NaOH), what is the stoichiometric ratio of $Al_2O_3 : NaOH : Sodium Aluminate formed$?

Accepted Answer

A) 1 : 2 : 2

Answer

B) 1 : 6 : 2

Answer

C) 2 : 2 : 1

Answer

D) 1 : 1 : 2

Question 5

A Science teacher set up four test tubes containing different metal strips and salt solutions:
• Tube P: Iron strip in $CuSO_4$ solution
• Tube Q: Copper strip in $FeSO_4$ solution
• Tube R: Zinc strip in $FeSO_4$ solution
• Tube S: Copper strip in $AgNO_3$ solution
In which of these test tubes will a displacement reaction occur?

Accepted Answer

D) Tubes P, R, and S only

Answer

A) Tubes P and Q only

Answer

B) Tubes P, Q, and R only

Answer

C) Tubes Q, R, and S only

Question 6

During the electrolytic refining of an impure copper block containing traces of gold, silver, zinc, and iron, which of the following statements correctly describes the setup and behavior of the components?

Accepted Answer

C) Impure copper is made the anode; Gold and silver settle below the anode as anode mud.

Answer

A) Pure copper is made the anode; Zinc deposits as anode mud.

Answer

B) Impure copper is made the cathode; Gold dissolves in the electrolyte.

Answer

D) Pure copper is made the cathode; Iron and zinc settle as anode mud.

Question 7

A local jeweler cleans old, dull gold ornaments using a freshly prepared solution called Aqua Regia. During this process, the weight of the ornament decreases. What is the composition of Aqua Regia, and why does gold dissolve in it?

Accepted Answer

A) Conc. $HNO_3$ and Conc. HCl in 1:3 ratio; dissolves gold by forming nascent chlorine.

Answer

B) Conc. HCl and Conc. $HNO_3$ in 1:3 ratio; dissolves gold by forming nitrous acid.

Answer

C) Conc. $H_2SO_4$ and Conc. $HNO_3$ in 3:1 ratio; dissolves gold by forming sulfur dioxide.

Answer

D) Conc. $HNO_3$ and Conc. HCl in 3:1 ratio; dissolves gold by forming hydrogen gas.

Question 8

A copper vessel kept in moist air for a long period of time loses its shiny brown surface and gains a dull green coating. Which of the following is the correct chemical formula of this green coating?

Accepted Answer

B) $CuCO_3 \cdot Cu(OH)_2$

Answer

A) $CuCO_3$ only

Answer

C) $CuSO_4 \cdot 5H_2O$

Answer

D) $CuO \cdot Cu(OH)_2$

Question 9

A non-metal X exists in two different allotropic forms, Y and Z. Allotrope Y is the hardest known natural substance with an extremely high melting point, whereas Allotrope Z is a good conductor of electricity and acts as a lubricant. Identify X, Y, and Z.

Accepted Answer

A) X = Carbon, Y = Diamond, Z = Graphite

Answer

B) X = Phosphorus, Y = Red\ P, Z = White\ P

Answer

C) X = Carbon, Y = Graphite, Z = Diamond

Answer

D) X = Sulfur, Y = Monoclinic, Z = Rhombic

Question 10

Galvanized iron pipes are protected against rusting by coating them with a thin layer of zinc. Even if the zinc coating is scratched or broken, the iron underneath does not rust. Why does this protection persist?

Accepted Answer

B) Zinc is more reactive than iron, so it oxidized preferentially (sacrificial protection).

Answer

A) Iron is more reactive than zinc and protects zinc.

Answer

C) Zinc reacts with iron to form a highly rust-resistant alloy.

Answer

D) The scratch is sealed automatically by the reaction of carbon dioxide with iron.