IMO Practice Test: Metals and Non-metals | Class 10 Chemistry

Question 1 of 13

Four metals W, X, Y, Z displace one another as: X displaces Y, Y displaces Z, but W displaces X. The order of decreasing reactivity is:

Z > Y > X > W

W > X > Y > Z

X > W > Y > Z

Y > Z > X > W

Explanation: A metal that displaces another is more reactive, so W > X > Y > Z.

Question 2 of 13

A metal M does not react with water or dilute acid but reacts with aqua regia. M is most likely:

Sodium

Iron

Gold

Zinc

Explanation: Gold is unreactive with water and acids but dissolves in aqua regia.

Question 3 of 13

Why can carbon NOT be used to extract sodium from its compounds?

Carbon is cheaper than sodium

Sodium is more reactive than carbon

Sodium has a low melting point

Carbon is a non-metal

Explanation: Sodium is more reactive than carbon, so carbon cannot reduce its compounds; electrolysis is used.

Question 4 of 13

A green coating slowly forms on a copper vessel left in moist air. This green substance is mainly:

copper oxide

basic copper carbonate

copper sulphide

copper chloride

Explanation: Moist air corrodes copper to basic copper carbonate, giving the green coating.

Question 5 of 13

Equal masses of Zn and Fe are added to separate beakers of dilute HCl. Compared with iron, zinc reacts:

slower, because it is less reactive

faster, because it is more reactive than iron

at the same rate

not at all

Explanation: Zinc is above iron in the reactivity series, so it reacts faster with dilute acid.

Question 6 of 13

An element forms an oxide that turns red litmus blue when dissolved in water. The element is most likely a:

non-metal

metal

noble gas

metalloid that is acidic

Explanation: A basic oxide (turns red litmus blue) is formed by a metal.

Question 7 of 13

In the reaction 2HgO → 2Hg + O₂, mercury is obtained simply by heating because mercury is:

highly reactive

very low in the reactivity series

a non-metal

an amphoteric metal

Explanation: Least reactive metals like mercury have unstable oxides that decompose to the metal on heating alone.

Question 8 of 13

Iron objects coated with zinc are protected even when the coating is scratched because:

zinc seals the scratch instantly

zinc is less reactive and protects iron

zinc is more reactive and corrodes in place of iron

iron becomes unreactive

Explanation: Zinc, being more reactive, corrodes preferentially (sacrificial protection), saving the iron.

Question 9 of 13

The molten compound electrolysed to obtain aluminium on a large scale is:

AlCl₃

Al₂O₃

Al₂(SO₄)₃

Al(OH)₃

Explanation: Aluminium is extracted by electrolysis of molten aluminium oxide, Al2O3.

Question 10 of 13

Which pair of changes both occur during the formation of CaCl₂?

Ca loses 2 e⁻; each Cl gains 1 e⁻

Ca gains 2 e⁻; each Cl loses 1 e⁻

Ca loses 1 e⁻; Cl gains 2 e⁻

Ca and Cl share electrons

Explanation: Ca (2,8,8,2) loses 2 electrons to form Ca2+, and two Cl atoms each gain one electron to form Cl-.

Question 11 of 13

A sulphide ore is converted to its oxide before reduction. The correct process and a by-product are:

calcination; CO₂

roasting; SO₂

reduction; CO

refining; H₂

Explanation: Sulphide ores are roasted in air, releasing SO2, e.g. 2ZnS + 3O2 -> 2ZnO + 2SO2.

Question 12 of 13

Why is solid NaCl a non-conductor while molten NaCl conducts electricity?

Solid NaCl has no ions

In the solid the ions are fixed; on melting they become free to move

Molten NaCl gains electrons

Solid NaCl is covalent

Explanation: Conduction needs mobile ions; ions are locked in the solid lattice but move freely when molten.

Question 13 of 13

A metal X is found native, does not tarnish easily and is used in jewellery. X most likely lies:

at the top of the reactivity series

just above hydrogen

at the bottom of the reactivity series

in the middle of the series

Explanation: Native, untarnishing jewellery metals like gold lie at the bottom (least reactive) of the series.

IMO Practice Test — Metals and Non-metals