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Chapter 1· States of Matter and Phase Changes
MCQs with Answers Try each one first: tap an option to check it, then read the reasoning and why the others are wrong.
A note about the questions
The wording follows published solved exercises and every answer was re-checked by hand, so the wording or the order of options may differ slightly from your print.
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Set A: Textbook exercise 10 MCQs The multiple-choice questions at the end of Chapter 1 in your book, in the book's option order.
Q1.1 States of Matter
Matter is present in neon signs in the state of:
(a) supercritical fluid (b) plasma (c) gas (d) liquid crystal Show answer and reasoning Answer (b) plasma
Step by step
A neon sign passes a high voltage through neon at low pressure. The gas is partly ionised into ions and electrons: plasma. Why the others are wrong
(a) a supercritical fluid needs very high pressure, not a glowing tube.(c) the neon starts as a gas, but while the sign glows it is ionised into plasma.(d) liquid crystals are used in display screens, not neon signs.Remember
Glowing gas tubes, lightning, welding arcs: plasma.
Q1.2 Branches of Chemistry
Hazardous effects of shopping bags are studied in:
(a) geochemistry (b) inorganic chemistry (c) analytical chemistry (d) environmental chemistry Show answer and reasoning Answer (d) environmental chemistry
Step by step
Plastic bags pollute soil and water. Effects of chemicals on the environment: environmental chemistry. Why the others are wrong
(a) geochemistry studies the composition of the Earth and its minerals.(b) plastics are organic polymers, and the question is about their effects on the environment.(c) analytical chemistry identifies and measures substances.Remember
Pollution = environmental chemistry.
Q1.3 Branches of Chemistry
The man-made polymer is:
(a) starch (b) polystyrene (c) protein (d) cellulose Show answer and reasoning Answer (b) polystyrene
Step by step
Natural polymers: starch, cellulose, proteins, nucleic acids. Synthetic polymer: polystyrene. Why the others are wrong
(a) starch is made by plants.(c) proteins are natural polymers.(d) cellulose is the natural polymer in plant cell walls.Remember
Poly-something from a factory = man-made.
Q1.4 Allotropy
The crystals of which substance have a rhombic shape?
(a) brass (b) sulphur (c) graphite (d) bronze Show answer and reasoning Answer (b) sulphur
Step by step
Allotropes of sulphur: rhombic and monoclinic. Why the others are wrong
(a) brass is an alloy of copper and zinc.(c) graphite has flat hexagonal layers.(d) bronze is an alloy of copper and tin.Remember
Rhombic and monoclinic: sulphur.
Q1.5 Solutions, Colloids and Suspensions
Which liquid among the following is a colloidal solution?
(a) milk (b) slaked lime used for whitewash (c) vinegar solution (d) mixture of AgCl in water Show answer and reasoning Answer (a) milk
Step by step
Vinegar: a true solution (acetic acid dissolved in water). Slaked lime and AgCl in water: visible particles that settle, so suspensions. Milk: particles do not settle and pass through filter paper, so a colloid. Why the others are wrong
(b) whitewash particles settle on standing: a suspension.(c) vinegar is a true solution.(d) AgCl is insoluble and settles: a suspension (precipitate).Remember
Milk, egg white, starch solution: colloids.
Q1.6 Elements, Compounds and Mixtures
Which of the following is a heterogeneous mixture?
(a) a solution of calcium hydroxide in water (b) a solution of potassium nitrate in water (c) hot chocolate (d) concrete mixture Show answer and reasoning Answer (d) concrete mixture
Step by step
Solutions are uniform throughout: homogeneous. Concrete: visibly different parts: heterogeneous. Why the others are wrong
(a) a solution is homogeneous.(b) a solution is homogeneous.(c) well-stirred hot chocolate looks the same throughout.Remember
Can you see different bits? Heterogeneous.
Q1.7 States of Matter
A state of matter whose properties are between those of liquids and crystalline solids is:
(a) liquid crystal (b) supercritical fluid (c) plasma (d) dark matter Show answer and reasoning Answer (a) liquid crystal
Step by step
Between liquid and solid: liquid crystal. Between liquid and gas: supercritical fluid. Why the others are wrong
(b) a supercritical fluid is between a liquid and a gas.(c) plasma is an ionised gas.(d) dark matter is an exotic state, not between liquid and solid.Remember
Liquid + crystal = liquid crystal.
Q1.8 Solutions, Colloids and Suspensions
When tiny visible particles of a substance are dispersed through a medium, the mixture is named as:
(a) true solution (b) colloid (c) suspension (d) saturated solution Show answer and reasoning Answer (c) suspension
Step by step
True solution: particles invisible. Colloid: particles invisible to the eye, do not settle. Suspension: particles visible, settle down. Why the others are wrong
(a) in a true solution the particles cannot be seen.(b) colloid particles are too small to see with the naked eye.(d) a saturated solution is a true solution holding the most solute.Remember
Visible particles = suspension.
Q1.9 Solubility
A solution of KClO₃ has a solubility of about 13.2 g per 100 cm³ at 40 °C. How will its solubility be affected if you decrease the temperature?
(a) the solubility will increase (b) the solubility will decrease (c) the solubility will remain the same (d) the solubility will first increase and then decrease Show answer and reasoning Answer (b) the solubility will decrease
Step by step
KClO₃ is more soluble when hot (its curve rises). Lower temperature: lower solubility. Why the others are wrong
(a) that would need a falling curve, as for gases.(c) that is nearly true only for NaCl.(d) the curve does not change direction.Remember
Rising curve: cool it and less dissolves.
Q1.10 Branches of Chemistry
You are studying the rate of hydrolysis of starch under different conditions of temperature. In which branch of chemistry will this topic fall?
(a) organic chemistry (b) analytical chemistry (c) biochemistry (d) physical chemistry Show answer and reasoning Answer (d) physical chemistry
Step by step
The key word is "rate". Predicting and changing rates of reactions is physical chemistry. Why the others are wrong
(a) starch is organic, but the topic is the rate, not the compound.(b) analytical chemistry identifies and measures substances.(c) starch is a biomolecule, but rates of reactions are physical chemistry.Remember
Rate, energy, conditions: physical chemistry.
Set B: More MCQs from this chapter 14 MCQs Extra questions on the same ideas, of the kind set in board papers and class tests.
QB1 Branches of Chemistry
The branch of chemistry that deals with reactions in the nucleus of an atom is:
(a) physical chemistry (b) nuclear chemistry (c) inorganic chemistry (d) astrochemistry Show answer and reasoning Answer (b) nuclear chemistry
Step by step
Ordinary reactions involve electrons; nuclear reactions involve the nucleus. Why the others are wrong
(a) physical chemistry studies behaviour, energy and rates.(c) inorganic chemistry studies compounds of elements other than carbon.(d) astrochemistry studies molecules in space.Remember
Nucleus = nuclear chemistry.
QB2 Branches of Chemistry
The design and synthesis of drugs is the work of:
(a) medicinal chemistry (b) geochemistry (c) polymer chemistry (d) environmental chemistry Show answer and reasoning Answer (a) medicinal chemistry
Step by step
Medicines: medicinal chemistry. Why the others are wrong
(b) geochemistry studies the Earth and its minerals.(c) polymer chemistry studies large chain molecules.(d) environmental chemistry studies chemicals in the environment.Remember
Medicine = medicinal.
QB3 States of Matter
Which state of matter is the most easily compressed?
(a) solid (b) liquid (c) gas (d) crystalline solid Show answer and reasoning Answer (c) gas
Step by step
Gas: widely spaced particles. Squeezing reduces the empty space. Why the others are wrong
(a) solid particles are packed tightly.(b) liquid particles are close together.(d) crystalline solids are almost incompressible.Remember
Far apart = easy to squeeze.
QB4 States of Matter
The only state of matter that does not need a container to keep its shape is:
(a) solid (b) liquid (c) gas (d) plasma Show answer and reasoning Answer (a) solid
Step by step
Liquids take the shape of the container; gases fill it. Solids have a definite shape. Why the others are wrong
(b) a liquid flows to the shape of its container.(c) a gas spreads to fill any container.(d) plasma is like a gas.Remember
Solids stand on their own.
QB5 States of Matter
Bose-Einstein condensate and dark matter are examples of:
(a) intermediate states (b) exotic states (c) allotropes (d) colloids Show answer and reasoning Answer (b) exotic states
Step by step
Intermediate states: supercritical fluids, liquid crystals. Exotic states: BEC, dark matter, quantum spin liquid. Why the others are wrong
(a) intermediate states lie between two ordinary states.(c) allotropes are forms of one element.(d) colloids are mixtures.Remember
Exotic = rare and unusual.
QB6 States of Matter
Graphene is:
(a) a single layer of carbon atoms in a hexagonal pattern (b) a liquid crystal (c) an ionic compound (d) many layers of carbon stacked together Show answer and reasoning Answer (a) a single layer of carbon atoms in a hexagonal pattern
Step by step
One layer: graphene. Many layers: graphite. Why the others are wrong
(b) it is a solid crystal.(c) it is pure carbon.(d) that is graphite.Remember
Graphene = one sheet of graphite.
QB7 Elements, Compounds and Mixtures
In water, hydrogen and oxygen are combined in a fixed ratio by mass of:
(a) 1 : 2 (b) 2 : 1 (c) 1 : 8 (d) 1 : 16 Show answer and reasoning Answer (c) 1 : 8
Step by step
Mass of H in H₂O = 2 × 1 = 2. Mass of O = 16. 2 : 16 = 1 : 8. Why the others are wrong
(a) that does not match any ratio in water.(b) 2 : 1 is the ratio of atoms, not of masses.(d) it forgets that there are two hydrogen atoms.Remember
Atoms 2 : 1, but masses 1 : 8.
QB8 Elements, Compounds and Mixtures
The components of a mixture can be separated by:
(a) chemical reactions only (b) physical methods (c) nuclear reactions (d) they cannot be separated Show answer and reasoning Answer (b) physical methods
Step by step
No chemical bonds between the components. So physical methods are enough. Why the others are wrong
(a) that is needed to break a compound.(c) nuclear reactions change elements.(d) mixtures are easy to separate.Remember
Mixture: physical separation. Compound: chemical reaction.
QB9 Allotropy
Ozone (O₃) and oxygen (O₂) are:
(a) isotopes (b) allotropes (c) compounds (d) mixtures Show answer and reasoning Answer (b) allotropes
Step by step
Same element, different structure: allotropes. Why the others are wrong
(a) isotopes differ in neutrons, not structure.(c) both contain only oxygen.(d) each is a pure form of oxygen.Remember
Same element, different form = allotrope.
QB10 Allotropy
Buckminster fullerene has the formula:
Show answer and reasoning Answer (c) C₆₀
Step by step
60 carbon atoms in a hollow sphere. Why the others are wrong
(a) six atoms make one hexagonal ring.(b) that is a smaller cage, not Buckminster fullerene.(d) not a fullerene formula used here.Remember
A football has 60 corners: C₆₀.
QB11 Solutions, Colloids and Suspensions
On filtration, the particles of which mixture are left behind on the filter paper?
(a) true solution (b) colloidal solution (c) suspension (d) all of these Show answer and reasoning Answer (c) suspension
Step by step
True solution: passes through. Colloid: passes through. Suspension: left as residue. Why the others are wrong
(a) solute particles pass through.(b) colloid particles also pass through.(d) only the suspension leaves a residue.Remember
Filter paper stops only suspensions.
QB12 Solubility
At 20 °C, the mass of NaCl that dissolves in 100 g of water to give a saturated solution is about:
(a) 3.6 g (b) 36 g (c) 204 g (d) 100 g Show answer and reasoning Answer (b) 36 g
Step by step
NaCl: 36 g per 100 g water at 20 °C. Why the others are wrong
(a) ten times too small.(c) that is table sugar.(d) far too large for salt.Remember
Salt 36, sugar 204.
QB13 Solubility
Soda water bottles are stored in a refrigerator because:
(a) gases are more soluble in water at low temperature (b) gases are less soluble in water at low temperature (c) sugar dissolves faster when cold (d) cold water has no dissolved gas Show answer and reasoning Answer (a) gases are more soluble in water at low temperature
Step by step
Gas solubility falls on heating. Cooling keeps more CO₂ dissolved. Why the others are wrong
(b) it is the other way round.(c) sugar dissolves more slowly when cold.(d) cold water holds more gas.Remember
Gases: colder dissolves more.
QB14 Solubility
A solution that can still dissolve more solute at a given temperature is:
(a) saturated (b) unsaturated (c) supersaturated (d) a suspension Show answer and reasoning Answer (b) unsaturated
Step by step
Below the maximum: unsaturated. At the maximum: saturated. Above it (unstable): supersaturated. Why the others are wrong
(a) a saturated solution cannot dissolve any more.(c) a supersaturated solution holds more than it normally can.(d) a suspension is not a solution.Remember
Un-saturated = not full yet.
