Subject chemistry

Written by Dr. Ayesha Nadeem (Chemistry)

COMSATS · کیمیا · 24 سوالات

نام: ____________________ تاریخ: ____________

The atomic number of oxygen is:
- A 6
- B 2
- C 16
- D 8
The molar mass of carbon dioxide (C = 12, O = 16) is:
- A 44 g/mol
- B 28 g/mol
- C 32 g/mol
- D 56 g/mol
A solution with a pH of 3 is:
- A Basic
- B Salty
- C Acidic
- D Neutral
The number of moles in 11 g of carbon dioxide (molar mass 44 g/mol) is:
- A 0.25
- B 4
- C 0.5
- D 11
The bonds between the atoms in a water molecule are:
- A Hydrogen only
- B Covalent
- C Metallic
- D Ionic
The metals in Group 1 of the periodic table are called:
- A Alkaline earth metals
- B Halogens
- C Noble gases
- D Alkali metals
The chemical formula of sulfuric acid is:
- A H₂SO₄
- B HNO₃
- C HCl
- D H₂CO₃
The chemical formula of methane is:
- A CH₄
- B C₂H₄
- C C₂H₆
- D CO₂
The number of electrons in a chloride ion (Cl⁻, atomic number 17) is:
- A 17
- B 18
- C 19
- D 16
Sodium hydroxide is:
- A A salt only
- B An acid
- C A base
- D A gas
The oxidation number of sulfur in SO₂ is:
- A +4
- B +6
- C −4
- D +2
When the temperature of a reaction is raised, its rate usually:
- A Stops
- B Stays the same
- C Decreases
- D Increases
The atomic number of nitrogen is:
- A 7
- B 6
- C 14
- D 8
The molar mass of water (H = 1, O = 16) is:
- A 16 g/mol
- B 18 g/mol
- C 34 g/mol
- D 10 g/mol
The number of moles in 22 g of carbon dioxide (molar mass 44 g/mol) is:
- A 1
- B 22
- C 2
- D 0.5
A solution with a pH of 11 is:
- A Basic
- B Salty
- C Neutral
- D Acidic
The bond in sodium chloride is:
- A Ionic
- B Metallic
- C Covalent
- D Hydrogen
The elements of Group 18 are called:
- A Noble gases
- B Halogens
- C Alkali metals
- D Transition metals
The chemical formula of sodium carbonate is:
- A Na₂CO₃
- B Na₂CO
- C NaHCO₃
- D NaCO₃
The chemical formula of ethane is:
- A C₂H₆
- B C₃H₈
- C C₂H₄
- D CH₄
The oxidation number of chlorine in sodium chloride is:
- A −1
- B −2
- C +1
- D 0
The number of neutrons in a carbon-14 atom (atomic number 6) is:
- A 8
- B 20
- C 14
- D 6
Which gas is produced when zinc reacts with dilute hydrochloric acid?
- A Hydrogen
- B Carbon dioxide
- C Oxygen
- D Chlorine
Rusting of iron needs:
- A Oxygen only
- B Oxygen and water
- C Water only
- D Nitrogen

جوابی کلید

1. D, 2. A, 3. C, 4. A, 5. B, 6. D, 7. A, 8. A, 9. B, 10. C, 11. A, 12. D, 13. A, 14. B, 15. D, 16. A, 17. A, 18. A, 19. A, 20. A, 21. A, 22. A, 23. A, 24. B

Oxygen has 8 protons.
12 + 2 × 16 = 44.
A pH below 7 is acidic.
Moles = 11 ÷ 44 = 0.25.
Hydrogen and oxygen share electrons.
Lithium, sodium and potassium are alkali metals.
Sulfuric acid has two hydrogen atoms, one sulfur atom and four oxygen atoms.
Methane has one carbon atom and four hydrogen atoms.
The ion has gained one electron.
It gives hydroxide ions in water.
Each oxygen is −2, so sulfur must be +4.
Particles collide more often and with more energy.
Nitrogen has 7 protons.
2 + 16 = 18.
22 ÷ 44 = 0.5.
A pH above 7 is basic.
Sodium gives an electron to chlorine.
They are very unreactive gases.
Two sodium ions balance one carbonate ion.
Ethane has two carbon atoms and six hydrogen atoms.
Sodium is +1, so chlorine is −1.
The neutrons are 14 − 6 = 8.
The metal displaces hydrogen from the acid.
Both oxygen and water must be present.