Chemistry common Questions for entrance exam from grade 9

1. What is the atomic number of an element?
   a) The number of protons in an atom 
   b) The total number of electrons in an atom 
   c) The number of neutrons in an atom 
   d) The total mass of an atom 

2. Which of the following is a chemical change?
   a) Ice melting 
   b) Water boiling 
   c) Iron rusting 
   d) Sugar dissolving in water 

3. What is the pH value of pure water at 25°C?
   a) 0 
   b) 7 
   c) 14 
   d) 10 

4. Which gas is produced when an acid reacts with a metal?
   a) Oxygen 
   b) Hydrogen 
   c) Carbon dioxide 
   d) Nitrogen 

5. What is the main component of air?
   a) Oxygen 
   b) Carbon dioxide 
   c) Nitrogen 
   d) Argon 

6. What type of bond is formed when electrons are shared between atoms?
   a) Ionic bond 
   b) Metallic bond 
   c) Covalent bond 
   d) Hydrogen bond 

7. Which of the following is an example of a mixture?
   a) Water (H₂O) 
   b) Sodium chloride (NaCl) 
   c) Air 
   d) Carbon dioxide (CO₂) 

8. What is the process called when a solid changes directly into a gas?
   a) Melting 
   b) Freezing 
   c) Sublimation 
   d) Condensation 

9. Which of the following elements is a noble gas?
   a) Oxygen 
   b) Nitrogen 
   c) Helium 
   d) Chlorine 

10. What is the law of conservation of mass?
    a) Mass can be created or destroyed in a chemical reaction. 
    b) Mass remains constant in a chemical reaction. 
    c) Mass is only present in solids. 
    d) Mass can change forms but not quantity. 

▎Answers:

1. a
2. c
3. b
4. b
5. c
6. c
7. c
8. c
9. c
10. b

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