IL106ILTS Science Chemistry Practice Exam
Question 1. Which of the following best defines the independent variable in a
controlled experiment?
A) The variable that is measured during the experiment
B) The variable that is kept constant throughout the experiment
C) The variable that the experimenter deliberately changes
D) The variable that is calculated from other data
Answer: C
Explanation: The independent variable is the factor that the researcher
manipulates to observe its effect on the dependent variable.
Question 2. In SI unit conversion, how many meters are in 3.5 kilometers?
A) 350 m
B) 3 500 m
C) 35 000 m
D) 0.35 m
Answer: B
Explanation: 1 km = 1 000 m, so 3.5 km = 3.5 × 1 000 = 3 500 m.
Question 3. A measurement reported as 12.30 g has how many significant figures?
A) 2
B) 3
C) 4
, IL106ILTS Science Chemistry Practice Exam
D) 5
Answer: C
Explanation: All non‑zero digits and any zeros between them or after the decimal
are significant; 12.30 has four.
Question 4. Which of the following is a chemical property of a substance?
A) Density
B
Question 4. Which of the following is a chemical property of a substance?
A) Density
B) Melting point
C) Reactivity with acids
D) Color
Answer: C
Explanation: Reactivity with acids describes how a substance chemically changes,
making it a chemical property.
Question 5. Which state of matter has a definite shape and volume?
A) Solid
B) Liquid
C) Gas
, IL106ILTS Science Chemistry Practice Exam
D) Plasma
Answer: A
Explanation: Solids maintain both shape and volume due to fixed particle
positions.
Question 6. A homogeneous mixture is best described as:
A) A mixture with visible layers
B) A mixture in which components are uniformly distributed
C) A mixture of two or more substances that cannot be separated by physical
means
D) A mixture that contains a solute that settles over time
Answer: B
Explanation: Homogeneous mixtures (solutions) have uniform composition
throughout.
Question 7. Dalton’s atomic theory incorrectly stated that atoms are:
A) Indivisible
B) Identical in mass for a given element
C) Capable of combining in simple whole‑number ratios
D) All of the above
Answer: A
, IL106ILTS Science Chemistry Practice Exam
Explanation: Modern experiments (e.g., Rutherford scattering) showed that atoms
have internal structure and are divisible.
Question 8. The number of neutrons in an atom is found by:
A) Subtracting the atomic number from the mass number
B) Adding the atomic number to the mass number
C) Multiplying the atomic number by the mass number
D) Dividing the mass number by the atomic number
Answer: A
Explanation: Neutrons = mass number – atomic number.
Question 9. The average atomic mass of chlorine is approximately 35.5 u. Which
isotopes contribute most to this value?
A) ^35Cl only
B) ^37Cl only
C) ^35Cl and ^37Cl in about 3:1 ratio
D) ^34Cl and ^36Cl equally
Answer: C
Explanation: Natural chlorine consists of ~75 % ^35Cl and ~25 % ^37Cl, giving an
average of 35.5 u.
Question 1. Which of the following best defines the independent variable in a
controlled experiment?
A) The variable that is measured during the experiment
B) The variable that is kept constant throughout the experiment
C) The variable that the experimenter deliberately changes
D) The variable that is calculated from other data
Answer: C
Explanation: The independent variable is the factor that the researcher
manipulates to observe its effect on the dependent variable.
Question 2. In SI unit conversion, how many meters are in 3.5 kilometers?
A) 350 m
B) 3 500 m
C) 35 000 m
D) 0.35 m
Answer: B
Explanation: 1 km = 1 000 m, so 3.5 km = 3.5 × 1 000 = 3 500 m.
Question 3. A measurement reported as 12.30 g has how many significant figures?
A) 2
B) 3
C) 4
, IL106ILTS Science Chemistry Practice Exam
D) 5
Answer: C
Explanation: All non‑zero digits and any zeros between them or after the decimal
are significant; 12.30 has four.
Question 4. Which of the following is a chemical property of a substance?
A) Density
B
Question 4. Which of the following is a chemical property of a substance?
A) Density
B) Melting point
C) Reactivity with acids
D) Color
Answer: C
Explanation: Reactivity with acids describes how a substance chemically changes,
making it a chemical property.
Question 5. Which state of matter has a definite shape and volume?
A) Solid
B) Liquid
C) Gas
, IL106ILTS Science Chemistry Practice Exam
D) Plasma
Answer: A
Explanation: Solids maintain both shape and volume due to fixed particle
positions.
Question 6. A homogeneous mixture is best described as:
A) A mixture with visible layers
B) A mixture in which components are uniformly distributed
C) A mixture of two or more substances that cannot be separated by physical
means
D) A mixture that contains a solute that settles over time
Answer: B
Explanation: Homogeneous mixtures (solutions) have uniform composition
throughout.
Question 7. Dalton’s atomic theory incorrectly stated that atoms are:
A) Indivisible
B) Identical in mass for a given element
C) Capable of combining in simple whole‑number ratios
D) All of the above
Answer: A
, IL106ILTS Science Chemistry Practice Exam
Explanation: Modern experiments (e.g., Rutherford scattering) showed that atoms
have internal structure and are divisible.
Question 8. The number of neutrons in an atom is found by:
A) Subtracting the atomic number from the mass number
B) Adding the atomic number to the mass number
C) Multiplying the atomic number by the mass number
D) Dividing the mass number by the atomic number
Answer: A
Explanation: Neutrons = mass number – atomic number.
Question 9. The average atomic mass of chlorine is approximately 35.5 u. Which
isotopes contribute most to this value?
A) ^35Cl only
B) ^37Cl only
C) ^35Cl and ^37Cl in about 3:1 ratio
D) ^34Cl and ^36Cl equally
Answer: C
Explanation: Natural chlorine consists of ~75 % ^35Cl and ~25 % ^37Cl, giving an
average of 35.5 u.
