Nature of Matter — JEE Main Chemistry MCQs with Solutions
Free JEE Main Chemistry Nature of Matter MCQs with step-by-step solutions (7 questions). Part of Some Basic Concepts of Chemistry. Practise online on Prepizo — no login needed.
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Questions with solutions
Q1 — Nature of Matter · medium · theory
Regarding the arrangement and motion of particles in the three states of matter, which statement is correct?
A. In gases the particles are held in a rigid, orderly lattice
B. In liquids the particles are farther apart than in gases
C. In gases the particles are far apart compared with solids and liquids and move easily and fast ✓ Correct
D. In solids the particles move around freely and rapidly
Solution: In gases the particles are far apart relative to solids and liquids and their movement is easy and fast. Liquid particles are closer than gas particles (not farther); solid particles are held close in a rigid orderly arrangement with little movement — the reverse of the other three options.
Q2 — Nature of Matter · medium · theory
Which of the following sets contains ONLY compounds?
A. Ammonia, sodium, nitrogen
B. Carbon dioxide, sugar solution, copper
C. Water, carbon dioxide, ammonia ✓ Correct
D. Water, air, oxygen
Solution: Water (H₂O), carbon dioxide (CO₂) and ammonia (NH₃) are all compounds — different elements combined in fixed ratios. The other sets contain elements (oxygen, sodium, nitrogen, copper) or mixtures (air, sugar solution), so they are not sets of only compounds.
Q3 — Nature of Matter · hard · theory
Which of the following statements is INCORRECT?
A. The constituents of a compound can be separated by simple physical methods ✓ Correct
B. Air is a mixture, not a compound
C. A compound has a fixed composition, whereas a mixture has a variable composition
D. The properties of a compound are usually different from those of its constituent elements
Solution: The incorrect statement is that the constituents of a compound can be separated by simple physical methods — in fact they can be separated only by chemical methods. Compounds do have a fixed composition, their properties differ from those of their elements (e.g. water vs hydrogen and oxygen gases), and air is indeed a mixture.
Q4 — Nature of Matter · medium · theory
Hydrogen burns with a pop sound and oxygen supports combustion, yet water — formed from these two elements — is used to extinguish fire. This is because:
A. Hydrogen and oxygen change into new elements inside water
B. Water contains hydrogen and oxygen in a variable ratio
C. The properties of a compound are different from those of its constituent elements ✓ Correct
D. Water is a mixture of hydrogen and oxygen and retains their properties
Solution: When elements combine to form a compound, the compound shows its own characteristic properties, different from those of the elements. Water is a compound (fixed 2:1 H:O ratio), not a mixture, so it does not behave like hydrogen or oxygen gas. No new elements are formed — the atoms are simply combined.
Q5 — Nature of Matter · medium · theory
Oxygen gas exists as O₂ molecules, each containing two atoms. Oxygen is nevertheless classified as an element because:
A. It is a gas at room temperature
B. All of its atoms are of one and the same type ✓ Correct
C. It contains two atoms joined together
D. It can be separated into simpler substances
Solution: An element consists of only one type of atom. Even though oxygen exists as diatomic O₂ molecules, both atoms are of the same kind, so it is an element — not a compound. A compound would need atoms of two or more different elements combined together.
Q6 — Nature of Matter · hard · theory
Consider the statements: (i) a mixture has its components in any ratio, (ii) a compound has its elements in a fixed definite ratio, (iii) a mixture can be separated by physical methods, (iv) a compound can be separated into its elements by physical methods. How many of these statements are correct?
A. Four
B. One
C. Two
D. Three ✓ Correct
Solution: Statements (i), (ii) and (iii) are correct — mixtures have a variable composition and can be separated physically, while a compound has a fixed ratio of elements. Statement (iv) is wrong: a compound can be separated into its elements only by chemical methods, not physical ones. Hence three statements are correct.
Q7 — Nature of Matter · medium · numerical
A gas is maintained at a temperature of 41 °F. Using °C = (°F − 32) × 5/9 and K = °C + 273.15, its temperature on the kelvin scale is:
A. 5 K
B. 314.15 K
C. 278.15 K ✓ Correct
D. 289.35 K
Solution: First convert to Celsius: °C = (41 − 32) × 5/9 = 9 × 5/9 = 5 °C. Then K = 5 + 273.15 = 278.15 K. Treating 41 °F as 41 °C gives the wrong 314.15 K; using 9/5 in place of 5/9 gives 289.35 K; forgetting to add 273.15 leaves only 5 K.