English

ہوم / مشق / NED / کیمیا / HSSC chemistry

HSSC chemistry

Written by Dr. Ayesha Nadeem (Chemistry)

25 سوالات: NED کیمیا، جوابات اور وضاحت کے ساتھ۔

جوابی کنجی کے ساتھ قابلِ پرنٹ ورک شیٹ

تمام سوالات جوابات کے ساتھ
  1. The number of protons in a sodium atom is:

    • 1 10
    • 2 23
    • 3 11
    • 4 12
    جواب دیکھیں

    درست جواب: 11

    The atomic number of sodium is 11.

    غلطی کی اطلاع دیں

  2. The number of electrons in a chloride ion (atomic number 17) is:

    • 1 16
    • 2 18
    • 3 17
    • 4 19
    جواب دیکھیں

    درست جواب: 18

    The ion has gained one electron.

    غلطی کی اطلاع دیں

  3. Boyle's law relates the pressure of a gas to its:

    • 1 Temperature at constant volume
    • 2 Density at constant pressure
    • 3 Volume at constant temperature
    • 4 Mass at constant volume
    جواب دیکھیں

    درست جواب: Volume at constant temperature

    P₁V₁ = P₂V₂ at constant temperature.

    غلطی کی اطلاع دیں

  4. According to Charles's law, the volume of a fixed mass of gas at constant pressure is proportional to:

    • 1 Its pressure
    • 2 Its absolute temperature
    • 3 Its density
    • 4 Its mass
    جواب دیکھیں

    درست جواب: Its absolute temperature

    V ÷ T is constant when T is in kelvin.

    غلطی کی اطلاع دیں

  5. The molar mass of sulfuric acid, H₂SO₄ (H = 1, S = 32, O = 16), is:

    • 1 96 g/mol
    • 2 82 g/mol
    • 3 98 g/mol
    • 4 64 g/mol
    جواب دیکھیں

    درست جواب: 98 g/mol

    2 + 32 + 64 = 98.

    غلطی کی اطلاع دیں

  6. The number of moles in 4.9 g of sulfuric acid (molar mass 98 g/mol) is:

    • 1 5
    • 2 0.05
    • 3 0.2
    • 4 0.5
    جواب دیکھیں

    درست جواب: 0.05

    4.9 ÷ 98 = 0.05.

    غلطی کی اطلاع دیں

  7. The empirical formula of glucose, C₆H₁₂O₆, is:

    • 1 C₂H₄O₂
    • 2 CH₂O
    • 3 C₆H₁₂O₆
    • 4 C₃H₆O₃
    جواب دیکھیں

    درست جواب: CH₂O

    The simplest ratio of the atoms is 1 : 2 : 1.

    غلطی کی اطلاع دیں

  8. The pH of a 0.001 M solution of hydrochloric acid is:

    • 1 11
    • 2 3
    • 3 1
    • 4 0.001
    جواب دیکھیں

    درست جواب: 3

    pH = −log 0.001 = 3.

    غلطی کی اطلاع دیں

  9. A buffer solution is a mixture of:

    • 1 A weak acid and its salt
    • 2 Water and a salt
    • 3 Two strong acids
    • 4 A strong acid and a strong base
    جواب دیکھیں

    درست جواب: A weak acid and its salt

    The pair resists a change of pH.

    غلطی کی اطلاع دیں

  10. A reaction is spontaneous at constant temperature and pressure when:

    • 1 ΔG is positive
    • 2 ΔG is negative
    • 3 ΔH is positive
    • 4 ΔS is zero
    جواب دیکھیں

    درست جواب: ΔG is negative

    A negative change in free energy means that the process can occur.

    غلطی کی اطلاع دیں

  11. A reaction has the rate law rate = k[A]². The order of the reaction is:

    • 1 Zero
    • 2 Third
    • 3 First
    • 4 Second
    جواب دیکھیں

    درست جواب: Second

    The order is the sum of the powers of the concentrations.

    غلطی کی اطلاع دیں

  12. In the electrolysis of molten sodium chloride, sodium is formed at the:

    • 1 Salt bridge
    • 2 Cathode
    • 3 Anode
    • 4 Electrolyte surface
    جواب دیکھیں

    درست جواب: Cathode

    Sodium ions gain electrons at the cathode.

    غلطی کی اطلاع دیں

  13. In an electrochemical cell, oxidation takes place at the:

    • 1 Cathode
    • 2 Salt bridge
    • 3 Voltmeter
    • 4 Anode
    جواب دیکھیں

    درست جواب: Anode

    Oxidation is loss of electrons at the anode.

    غلطی کی اطلاع دیں

  14. Which reagent is decolourised by an alkene?

    • 1 Copper sulfate solution
    • 2 Limewater
    • 3 Bromine water
    • 4 Litmus solution
    جواب دیکھیں

    درست جواب: Bromine water

    The bromine adds across the double bond.

    غلطی کی اطلاع دیں

  15. The IUPAC name of CH₃CH=CH₂ is:

    • 1 Propane
    • 2 Propyne
    • 3 Propene
    • 4 Butene
    جواب دیکھیں

    درست جواب: Propene

    The three carbon chain with a double bond is propene.

    غلطی کی اطلاع دیں

  16. Ethanol and dimethyl ether, both C₂H₆O, are examples of:

    • 1 Functional group isomers
    • 2 Optical isomers
    • 3 Chain isomers
    • 4 Position isomers
    جواب دیکھیں

    درست جواب: Functional group isomers

    They have the same formula but different functional groups.

    غلطی کی اطلاع دیں

  17. Benzene reacts with a mixture of concentrated nitric acid and sulfuric acid to give:

    • 1 Chlorobenzene
    • 2 Phenol
    • 3 Nitrobenzene
    • 4 Cyclohexane
    جواب دیکھیں

    درست جواب: Nitrobenzene

    This is the nitration of benzene.

    غلطی کی اطلاع دیں

  18. Aldehydes can be tested with:

    • 1 Litmus paper
    • 2 Tollens' reagent
    • 3 Limewater
    • 4 Bromine water
    جواب دیکھیں

    درست جواب: Tollens' reagent

    An aldehyde forms a silver mirror with Tollens' reagent.

    غلطی کی اطلاع دیں

  19. The hybridisation of the carbon atoms in ethyne (C₂H₂) is:

    • 1 sp³d
    • 2 sp³
    • 3 sp
    • 4 sp²
    جواب دیکھیں

    درست جواب: sp

    Each carbon has a triple bond and one other single bond.

    غلطی کی اطلاع دیں

  20. The bond angle in a water molecule is about:

    • 1 104.5°
    • 2 180°
    • 3 109.5°
    • 4 120°
    جواب دیکھیں

    درست جواب: 104.5°

    The two lone pairs reduce the angle from 109.5°.

    غلطی کی اطلاع دیں

  21. The high boiling point of hydrogen fluoride compared with hydrogen chloride is because of:

    • 1 A lower molar mass
    • 2 Metallic bonding
    • 3 Hydrogen bonding
    • 4 Ionic bonding
    جواب دیکھیں

    درست جواب: Hydrogen bonding

    Hydrogen fluoride forms hydrogen bonds.

    غلطی کی اطلاع دیں

  22. Going down a group of the periodic table, the first ionisation energy usually:

    • 1 Decreases
    • 2 Stays the same
    • 3 Doubles
    • 4 Increases
    جواب دیکھیں

    درست جواب: Decreases

    The outer electron is further from the nucleus.

    غلطی کی اطلاع دیں

  23. Which of these is a Lewis acid?

    • 1 OH⁻
    • 2 H₂O
    • 3 NH₃
    • 4 BF₃
    جواب دیکھیں

    درست جواب: BF₃

    BF₃ can accept a pair of electrons.

    غلطی کی اطلاع دیں

  24. The catalyst used in the Haber process for ammonia is:

    • 1 Nickel
    • 2 Iron
    • 3 Vanadium pentoxide
    • 4 Platinum
    جواب دیکھیں

    درست جواب: Iron

    Finely divided iron is the catalyst.

    غلطی کی اطلاع دیں

  25. Which gas is mainly responsible for acid rain?

    • 1 Nitrogen
    • 2 Sulfur dioxide
    • 3 Helium
    • 4 Argon
    جواب دیکھیں

    درست جواب: Sulfur dioxide

    Sulfur dioxide forms sulfurous and sulfuric acid in water.

    غلطی کی اطلاع دیں