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📚 Questions about alkanes and alkynes:

1. Which of the following is the general formula for alkanes?
    * A. CnH2n
    * B. CnH2n+2
    * C. CnH2n-2
    * D. CnH2n-4

2. Which of the following is the general formula for alkenes?
    * A. CnH2n
    * B. CnH2n+2
    * C. CnH2n-2
    * D. CnH2n-4

3. Which of the following is the general formula for alkynes?
    * A. CnH2n
    * B. CnH2n+2
    * C. CnH2n-2
    * D. CnH2n-4

4. Which of the following is an alkane?
    * A. CH4
    * B. C2H4
    * C. C2H2
    * D. C3H6

5. Which of the following is an alkene?
    * A. CH4
    * B. C2H4
    * C. C2H2
    * D. C3H6

6. Which of the following is an alkyne?
    * A. CH4
    * B. C2H4
    * C. C2H2
    * D. C3H6

7. Which of the following alkanes has the highest boiling point?
    * A. methane
    * B. ethane
    * C. propane
    * D. butane

8. Which of the following alkenes has the highest boiling point?
    * A. ethene
    * B. propene
    * C. butene
    * D. pentene

9. Which of the following alkynes has the highest boiling point?
    * A. ethyne
    * B. propyne
    * C. butyne
    * D. pentyne

10. Which of the following alkanes is the most reactive?
    * A. methane
    * B. ethane
    * C. propane
    * D. butane

11. Which of the following alkenes is the most reactive?
    * A. ethene
    * B. propene
    * C. butene
    * D. pentene

12. Which of the following alkynes is the most reactive?
    * A. ethyne
    * B. propyne
    * C. butyne
    * D. pentyne

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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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What is the function of the cell membrane?
So‘rovnoma
  •   a) Protection and support
  •   b) Control of substances entering and leaving the cell
  •   c) Protein synthesis
  •   d) Storage of genetic material
18 ta ovoz


Which molecule is split during the light-dependent reactions to release oxygen?
So‘rovnoma
  •   a) Water
  •   b) Carbon dioxide
  •   c) Glucose
  •   d) ATP
16 ta ovoz

8 ta oxirgi post ko‘rsatilgan.