Browse topic-based Class 9 Science practice sets.
189 practice sets · Page 4 of 10
What is the bond formed when two atoms share electrons?
Ionic bond
Metallic bond
Covalent bond
Hydrogen bond
Correct Answer: C — Covalent bond
Explanation:
A covalent bond is formed by sharing electrons between atoms.
What is the chemical formula for calcium chloride?
CaCl
Ca₂Cl₂
Ca₂Cl
CaCl₂
Correct Answer: D — CaCl₂
Explanation:
Calcium chloride contains one calcium atom and two chlorine atoms.
Which of the following elements is inert?
Oxygen
Neon
Nitrogen
Hydrogen
Correct Answer: B — Neon
Explanation:
Neon is a noble gas and is chemically inert.
Which of the following is a diatomic molecule?
Oxygen (O₂)
Nitrogen (N₂)
Chlorine (Cl₂)
All of the mentioned
Correct Answer: D — All of the mentioned
Explanation:
Oxygen, nitrogen, and chlorine all exist as diatomic molecules.
What is the empirical formula of glucose (C₆H₁₂O₆)?
C₆H₁₂O₆
CH₂O
CH₃O
C₁₂H₂O₁₂
Correct Answer: B — CH₂O
Explanation:
The empirical formula represents the simplest whole-number ratio of atoms in a compound.
Which of the following is a molecule made up of two identical atoms?
Water (H₂O)
Oxygen (O₂)
Methane (CH₄)
Carbon dioxide (CO₂)
Correct Answer: B — Oxygen (O₂)
Explanation:
Oxygen molecules consist of two oxygen atoms bonded together.
Which of the following particles are found in the nucleus of an atom?
Only neutrons
Electrons and neutrons
Protons and neutrons
Electrons and protons
Correct Answer: C — Protons and neutrons
Explanation:
The nucleus contains protons and neutrons.
What is an atom?
The smallest particle of an element
A particle of a compound
A type of molecule
A part of a molecule
Correct Answer: A — The smallest particle of an element
Explanation:
An atom is the smallest particle of an element that retains its chemical properties.
Which of the following is a technique used to separate different colored pigments in a mixture?
Distillation
Chromatography
Filtration
Centrifugation
Correct Answer: B — Chromatography
Explanation:
Chromatography separates substances based on different rates of movement.
What is the main characteristic of a homogeneous mixture?
The components settle over time
The components are visibly different
The components are uniformly distributed
The components can be separated by physical means
Correct Answer: C — The components are uniformly distributed
Explanation:
A homogeneous mixture has a uniform composition throughout.
Which of the following is an example of a compound?
Saltwater
Oxygen
Sand
Water
Correct Answer: D — Water
Explanation:
Water is a compound made of hydrogen and oxygen chemically combined.
Which of the following is an example of a heterogeneous mixture?
Concrete
Vinegar
Milk
Saltwater
Correct Answer: A — Concrete
Explanation:
Concrete is a heterogeneous mixture because its components are not uniformly distributed.
What type of mixture is air?
Heterogeneous mixture
Homogeneous mixture
Compound
Pure substance
Correct Answer: B — Homogeneous mixture
Explanation:
Air is a homogeneous mixture of gases uniformly distributed.
Which of the following is an example of a pure substance?
Hydrogen
Salt solution
Sand and water
Air
Correct Answer: A — Hydrogen
Explanation:
Hydrogen is a pure substance consisting of only one type of atom.
What is a colloid?
A solution in which the solute is in large quantities
A homogeneous mixture with small particles
A heterogeneous mixture with tiny particles
A homogeneous mixture with large particles
Correct Answer: C — A heterogeneous mixture with tiny particles
Explanation:
A colloid is a heterogeneous mixture with very small suspended particles.
What is the key characteristic of a heterogeneous mixture?
Components are uniformly distributed
Components are chemically bonded
Components form a single phase
Components are not uniformly distributed
Correct Answer: D — Components are not uniformly distributed
Explanation:
In a heterogeneous mixture, components are unevenly distributed.
Which of the following substances is a pure element?
Copper
Sodium chloride
Air
Saltwater
Correct Answer: A — Copper
Explanation:
Copper is a pure element made of only copper atoms.
What is the main cause of evaporation?
Decrease in temperature
Increase in pressure
Increase in temperature
Decrease in volume
Correct Answer: C — Increase in temperature
Explanation:
Higher temperature increases particle energy, causing evaporation.
Which of the following changes is reversible?
Melting of wax
Burning of paper
Rusting of iron
Cooking of food
Correct Answer: A — Melting of wax
Explanation:
Melted wax solidifies again on cooling, making the change reversible.
What is the boiling point of water?
0°C
100°C
50°C
200°C
Correct Answer: B — 100°C
Explanation:
Water boils at 100°C under standard atmospheric pressure.
