Q.1: Which of the following is a basic unit in chemistry?
(a) Mole
(b) Gram
(c) Meter
(d) Liter
Q.2: What is the empirical formula of a compound with 40% carbon, 6.7% hydrogen, and 53.3% oxygen?
(a) CHO
(b) CHO₂
(c) CH₂O
(d) CH₃O
Q.3: The molar mass of water (H₂O) is:
(a) 16 g/mol
(b) 18 g/mol
(c) 20 g/mol
(d) 22 g/mol
Q.4: Avogadro’s number is:
(a) 6.022 × 10²²
(b) 6.022 × 10²³
(c) 6.022 × 10²⁴
(d) 6.022 × 10²⁵
Q.5: The law of conservation of mass states that:
(a) Mass can be created
(b) Mass can be destroyed
(c) Mass can neither be created nor destroyed
(d) Mass is variable
Q.6: One mole of a substance contains:
(a) 6.022 × 10²³ atoms
(b) 6.022 × 10²³ molecules
(c) 6.022 × 10²³ ions
(d) All of the above
Q.7: Which of the following is the correct molecular formula for glucose?
(a) CH₂O
(b) C₂H₄O₂
(c) C₆H₁₂O₆
(d) C₁₂H₂₂O₁₁
Q.8: Which of the following statements is incorrect regarding atomic mass?
(a) Atomic mass is measured in atomic mass units (amu)
(b) Atomic mass is the mass of an individual atom
(c) Atomic mass is the same as atomic number
(d) Atomic mass is the weighted average mass of the atoms in a naturally occurring sample
Q.9: Which of the following laws is also known as the law of definite proportions?
(a) Law of conservation of mass
(b) Law of multiple proportions
(c) Law of constant composition
(d) Avogadro’s law
Q.10: The mass percentage of an element in a compound is given by:
(a) (Atomic mass of element / Molar mass of compound) × 100
(b) (Number of atoms of element × Atomic mass of element / Molar mass of compound) × 100
(c) (Number of moles of element / Molar mass of compound) × 100
(d) (Number of atoms of element / Molar mass of compound) × 100
Q.11: What is the molar volume of an ideal gas at STP?
(a) 22.4 L
(b) 24.5 L
(c) 20.8 L
(d) 18.6 L
Q.12: Which of the following compounds has the highest percentage of carbon?
(a) CH₄
(b) C₂H₆
(c) C₃H₈
(d) C₄H₁₀
Q.13: A pure substance which contains only one type of atom is called ————–.
(a) An element
(b) a compound
(c) a solid
(d) a liquid
Q.14: The molecular weight of a substance is:
(a) The sum of the atomic weights of the atoms in its molecular formula
(b) The sum of the atomic weights of the atoms in its empirical formula
(c) The weight of one mole of its molecules
(d) Both (a) and (c)
Q.15: The density of a substance is defined as:
(a) Mass per unit volume
(b) Volume per unit mass
(c) Mass per unit area
(d) Area per unit mass
Q.16: The empirical formula of a compound represents:
(a) The actual number of atoms in a molecule
(b) The simplest whole-number ratio of atoms in the compound
(c) The structure of the molecule
(d) The molecular geometry
Q.17: Which of the following is not a state of matter?
(a) Solid
(b) Liquid
(c) Gas
(d) Light
Q.18: The smallest particle that can take part in chemical reactions is ————–.
(a) Atom
(b) molecule
(c) Both (a) and (b)
(d) none of these
Q.19: The Avogadro constant is used to calculate:
(a) Volume of a gas
(b) Number of particles in a mole
(c) Density of a solid
(d) Molarity of a solution
Q.20: The significant figures in 0.00051 are ————–.
(a) 5
(b) 3
(c) 2
(d) 26
Q.21: Which of the following is an example of a heterogeneous mixture?
(a) Saltwater
(b) Air
(c) Soil
(d) Vinegar
Q.22: The SI unit of amount of substance is:
(a) Kilogram
(b) Mole
(c) Liter
(d) Meter
Q.23: What is the percentage composition of hydrogen in water (H₂O)?
(a) 11.1%
(b) 8.9%
(c) 5.6%
(d) 20%
Q.24: The number of significant figures in 6.02 x 1023 is ______.
(a) 23
(b) 3
(c) 4
(d) 26
Q.25: Which of the following has the highest number of molecules?
(a) 1 g of H₂
(b) 1 g of O₂
(c) 1 g of N₂
(d) 1 g of CO₂
Q.26: What is the molar mass of ethanol (C₂H₅OH)?
(a) 34 g/mol
(b) 46 g/mol
(c) 28 g/mol
(d) 44 g/mol
Q.27: The prefix 103 is _____.
(a) giga
(b) exa
(c) kilo
(d) mega
Q.28: The ratio of the number of moles of solute to the volume of solution in liters is called:
(a) Molality
(b) Molarity
(c) Normality
(d) Formality
Q.29: A solution contains 5.85 g of NaCl in 500 mL of solution. The molarity of the solution is:
(a) 0.1 M
(b) 0.2 M
(c) 0.5 M
(d) 1.0 M
Q.30: The sum of the atomic masses of all the atoms in a formula unit of a compound is known as:
(a) Molecular mass
(b) Formula mass
(c) Molar mass
(d) Equivalent mass
Q.31: The volume occupied by one mole of an ideal gas at STP is:
(a) 22.4 liters
(b) 24.0 liters
(c) 20.5 liters
(d) 18.0 liters
Q.32: Which of the following represents the largest mass?
(a) 1 mole of H₂O
(b) 1 mole of CO₂
(c) 1 mole of NaCl
(d) 1 mole of CH₄
Q.33: The mass of an atom of carbon is ————–.
(a) 1g
(b) 1.99 x 10-23 g
(c) 1/12 g
(d) 1.99 x 1023 g
Q.34: A measured temperature on Fahrenheit scale is 98.60F. What will this reading be on the Celsius Scale?
(a) 40 ℃
(b) 94 ℃
(c) 37 ℃
(d) 30 ℃
Q.35: Which of the following pairs of gases contains the same number of molecules?
(a) 16 g of O2 and 14 g of N2
(b) 6 g of O2 and 22 g of CO2
(c) 28 g of N2 and 22 g of CO2
(d) 32 g of CO2 and 32g of N2
Q.36: Which of the following is a pure substance?
(a) Air
(b) Milk
(c) Carbon dioxide
(d) Vinegar
Q.37: The molecular formula of benzene is:
(a) C₆H₆
(b) C₆H₁₂
(c) C₁₂H₆
(d) C₁₂H₁₂
Q.38: What is the mass of 1 mole of sodium chloride (NaCl)?
(a) 23 g
(b) 35.5 g
(c) 58.5 g
(d) 18 g
Q.39: The simplest whole number ratio of atoms in a compound is given by the:
(a) Molecular formula
(b) Structural formula
(c) Empirical formula
(d) None of the above
Q.40: The number of moles of solute present in 1 kg of solvent is called:
(a) Molarity
(b) Molality
(c) Normality
(d) Formality
Q.41: The molecular formula of acetylene is:
(a) C₂H₄
(b) C₃H₆
(c) C₂H₂
(d) C₄H₄
Q.42: The SI unit of pressure is:
(a) Pascal
(b) Atmosphere
(c) Torr
(d) Bar
Q.43: In a chemical reaction, the limiting reagent is:
(a) The reagent that is present in excess
(b) The reagent that determines the amount of product formed
(c) The reagent that reacts with water
(d) The reagent that speeds up the reaction
Q.44: The empirical formula of a compound with a molecular formula of C₆H₁₂O₆ is:
(a) CH₂O
(b) CHO
(c) C₂H₄O₂
(d) C₆H₆O₆
Q.45: The atomic mass of carbon is 12.01. This means that:
(a) Every carbon atom weighs 12.01 g
(b) The average mass of a carbon atom is 12.01 amu
(c) Carbon is the heaviest element
(d) Carbon atoms always have a mass of 12.01 amu
Q.46: Which of the following is not a physical quantity?
(a) Density
(b) Temperature
(c) Molality
(d) Concentration
Q.47: The number of atoms in one molecule of water (H₂O) is:
(a) 2
(b) 3
(c) 4
(d) 5
Q.48: The molar mass of calcium carbonate (CaCO₃) is:
(a) 40 g/mol
(b) 100 g/mol
(c) 60 g/mol
(d) 50 g/mol
Q.49: Which of the following is a unit of concentration?
(a) Mole
(b) Molecule
(c) Molality
(d) Mass
Q.50: If 5 moles of A react with 10 moles of B according to the reaction A + 2B → AB₂, which is the limiting reagent?
(a) A
(b) B
(c) AB₂
(d) None
Q.53: The number 0.00045 expressed in scientific notation is:
(a) 4.5 × 10³
(b) 4.5 × 10⁻³
(c) 4.5 × 10⁻⁴
(d) 4.5 × 10⁴
Q.54: Which of the following is correctly expressed in scientific notation?
(a) 2.34 × 10⁷
(b) 23.4 × 10⁷
(c) 0.234 × 10⁸
(d) 234 × 10⁶
Q.55: The atomic mass unit (amu) is defined as:
(a) The mass of one atom of hydrogen
(b) 1/12 the mass of one atom of carbon-12
(c) The mass of one proton
(d) The mass of one electron
Q.56: Which of the following has a mass of approximately 1 amu?
(a) Neutron
(b) Electron
(c) Photon
(d) None
Q.57: The mass percent of a solute in a solution is defined as:
(a) The mass of solute per unit volume of solution
(b) The mass of solute divided by the total mass of solution, multiplied by 100
(c) The mass of solute divided by the mass of solvent, multiplied by 100
(d) The volume of solute divided by the total volume of solution, multiplied by 100
Q.58: If 10 grams of NaCl is dissolved in 90 grams of water, what is the mass percent of NaCl in the solution?
(a) 10%
(b) 11.1%
(c) 9%
(d) 1%
Q.59: The mole fraction of a component in a mixture is defined as:
(a) The ratio of its moles to the total moles of all components in the mixture
(b) The ratio of its moles to the mass of the mixture
(c) The ratio of its moles to the volume of the mixture
(d) The ratio of its moles to its atomic mass
Q.60: In a mixture of gases, if the mole fraction of oxygen (O₂) is 0.2, what is the mole fraction of nitrogen (N₂) if they are the only components?
(a) 0.8
(b) 0.2
(c) 1.2
(d) 0.5
Q.61: Molarity is defined as:
(a) The number of moles of solute per kilogram of solvent
(b) The number of moles of solute per liter of solution
(c) The mass of solute per liter of solution
(d) The mass of solute per kilogram of solvent
Q.62: Molality is defined as:
(a) The number of moles of solute per kilogram of solvent
(b) The number of moles of solute per liter of solution
(c) The mass of solute per liter of solution
(d) The mass of solute per kilogram of solvent
Q.63: What is the molarity of a solution containing 0.5 moles of NaCl dissolved in 2 liters of water?
(a) 0.25 M
(b) 1.0 M
(c) 2.5 M
(d) 0.1 M
Q.64: What is the molality of a solution containing 30 grams of glucose (C₆H₁₂O₆) dissolved in 500 grams of water?
(a) 0.06 m
(b) 0.6 m
(c) 6 m
(d) 60 m
Q.65: If a solution having molarity M₁ and volume V₁ is diluted to volume V₂ so that the new molarity is M₂, then which equation represents the relationship between M₁, V₁, V₂, and M₂?
(a) M₁V₁ = M₂V₂
(b) M₁V₂ = M₂V₁
(c) M₂V₁ = M₁V₂
(d) M₂V₂ = M₁V₁
Q.66: A solution with a molarity of 2.0 M and a volume of 500 mL is diluted to 1000 mL. What is the new molarity of the solution?
(a) 0.5 M
(b) 1.0 M
(c) 2.0 M
(d) 4.0 M