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HSSC chemistry

Written by Dr. Ayesha Nadeem (Chemistry)

NED · Chemistry · 25 questions

Name: ____________________ Date: ____________

The number of protons in a sodium atom is:
- A 10
- B 23
- C 11
- D 12
The number of electrons in a chloride ion (atomic number 17) is:
- A 16
- B 18
- C 17
- D 19
Boyle's law relates the pressure of a gas to its:
- A Temperature at constant volume
- B Density at constant pressure
- C Volume at constant temperature
- D Mass at constant volume
According to Charles's law, the volume of a fixed mass of gas at constant pressure is proportional to:
- A Its pressure
- B Its absolute temperature
- C Its density
- D Its mass
The molar mass of sulfuric acid, H₂SO₄ (H = 1, S = 32, O = 16), is:
- A 96 g/mol
- B 82 g/mol
- C 98 g/mol
- D 64 g/mol
The number of moles in 4.9 g of sulfuric acid (molar mass 98 g/mol) is:
- A 5
- B 0.05
- C 0.2
- D 0.5
The empirical formula of glucose, C₆H₁₂O₆, is:
- A C₂H₄O₂
- B CH₂O
- C C₆H₁₂O₆
- D C₃H₆O₃
The pH of a 0.001 M solution of hydrochloric acid is:
- A 11
- B 3
- C 1
- D 0.001
A buffer solution is a mixture of:
- A A weak acid and its salt
- B Water and a salt
- C Two strong acids
- D A strong acid and a strong base
A reaction is spontaneous at constant temperature and pressure when:
- A ΔG is positive
- B ΔG is negative
- C ΔH is positive
- D ΔS is zero
A reaction has the rate law rate = k[A]². The order of the reaction is:
- A Zero
- B Third
- C First
- D Second
In the electrolysis of molten sodium chloride, sodium is formed at the:
- A Salt bridge
- B Cathode
- C Anode
- D Electrolyte surface
In an electrochemical cell, oxidation takes place at the:
- A Cathode
- B Salt bridge
- C Voltmeter
- D Anode
Which reagent is decolourised by an alkene?
- A Copper sulfate solution
- B Limewater
- C Bromine water
- D Litmus solution
The IUPAC name of CH₃CH=CH₂ is:
- A Propane
- B Propyne
- C Propene
- D Butene
Ethanol and dimethyl ether, both C₂H₆O, are examples of:
- A Functional group isomers
- B Optical isomers
- C Chain isomers
- D Position isomers
Benzene reacts with a mixture of concentrated nitric acid and sulfuric acid to give:
- A Chlorobenzene
- B Phenol
- C Nitrobenzene
- D Cyclohexane
Aldehydes can be tested with:
- A Litmus paper
- B Tollens' reagent
- C Limewater
- D Bromine water
The hybridisation of the carbon atoms in ethyne (C₂H₂) is:
- A sp³d
- B sp³
- C sp
- D sp²
The bond angle in a water molecule is about:
- A 104.5°
- B 180°
- C 109.5°
- D 120°
The high boiling point of hydrogen fluoride compared with hydrogen chloride is because of:
- A A lower molar mass
- B Metallic bonding
- C Hydrogen bonding
- D Ionic bonding
Going down a group of the periodic table, the first ionisation energy usually:
- A Decreases
- B Stays the same
- C Doubles
- D Increases
Which of these is a Lewis acid?
- A OH⁻
- B H₂O
- C NH₃
- D BF₃
The catalyst used in the Haber process for ammonia is:
- A Nickel
- B Iron
- C Vanadium pentoxide
- D Platinum
Which gas is mainly responsible for acid rain?
- A Nitrogen
- B Sulfur dioxide
- C Helium
- D Argon

Answer key

1. C, 2. B, 3. C, 4. B, 5. C, 6. B, 7. B, 8. B, 9. A, 10. B, 11. D, 12. B, 13. D, 14. C, 15. C, 16. A, 17. C, 18. B, 19. C, 20. A, 21. C, 22. A, 23. D, 24. B, 25. B

The atomic number of sodium is 11.
The ion has gained one electron.
P₁V₁ = P₂V₂ at constant temperature.
V ÷ T is constant when T is in kelvin.
2 + 32 + 64 = 98.
4.9 ÷ 98 = 0.05.
The simplest ratio of the atoms is 1 : 2 : 1.
pH = −log 0.001 = 3.
The pair resists a change of pH.
A negative change in free energy means that the process can occur.
The order is the sum of the powers of the concentrations.
Sodium ions gain electrons at the cathode.
Oxidation is loss of electrons at the anode.
The bromine adds across the double bond.
The three carbon chain with a double bond is propene.
They have the same formula but different functional groups.
This is the nitration of benzene.
An aldehyde forms a silver mirror with Tollens' reagent.
Each carbon has a triple bond and one other single bond.
The two lone pairs reduce the angle from 109.5°.
Hydrogen fluoride forms hydrogen bonds.
The outer electron is further from the nucleus.
BF₃ can accept a pair of electrons.
Finely divided iron is the catalyst.
Sulfur dioxide forms sulfurous and sulfuric acid in water.