SENIOR ELEMENTARY TEACHER CHEMISTRY PAST PAPER 11-05-2026
FPSC 5 years
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چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
- 100.256°C
- 100°C
- 101.256°C
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- ΔTb = Kb × m × i = 0.512 × 0.5 × 1 = 0.256°C
- Boiling point = 100 + 0.256 = 100.256°C.
Last verified on 19-05-2026
کسی مادے کا ٹرپل پوائنٹ کیا ہوتا ہے؟
- Point where solid, liquid, and gas coexist in equilibrium
- Point where only solid and liquid coexist
- Point where only liquid and gas coexist
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- The triple point is a special thermodynamic condition of a substance.
- At this point, all three phases exist together.
- These phases are solid, liquid, and gas.
- They remain in equilibrium at a specific temperature and pressure.
- It is a fixed and unique point for each substance.
Last verified on 19-05-2026
کس ری ایکشن میں ری ایکٹنٹس کے تمام ایٹم پروڈکٹ میں شامل ہوتے ہیں؟
- Combustion of methane
- Hydrogenation of alkene
- Substitution reaction
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- In some chemical reactions, all atoms of reactants are completely retained in the final product.
- No atom is lost or removed during the reaction.
- Such reactions are typically addition reactions.
- Hydrogenation of alkenes is a common example.
Last verified on 19-05-2026
اروماتک نائٹریشن میں کون سا الیکٹروفائل استعمال ہوتا ہے؟
- NO⁺
- NO₂⁻
- NO₂⁺
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- The active electrophile in nitration of benzene is nitronium ion (NO₂⁺).
- It is generated from a mixture of concentrated HNO₃ and H₂SO₄.
Last verified on 19-05-2026
- −Ea/R
- +Ea/R
- −R/Ea
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- The Arrhenius plot relates the rate constant (k) with temperature (T).
- When we plot ln k vs 1/T, we get a straight line.
- Whose slope is negative activation energy divided by gas constant.
Last verified on 19-05-2026
- Hyperbola
- Parabola
- Straight line
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- According to the Arrhenius equation, the relationship between rate constant (k) and temperature (T) is exponential.
- When we plot ln k vs 1/T, it gives a straight line.
- It showing a linear relationship.
Last verified on 19-05-2026
- Both increase
- Both decrease
- Liquid viscosity decreases, gas viscosity increases
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Temperature affects liquids and gases differently in terms of viscosity.
When temperature increases:
- Liquids: viscosity decreases
- Gases: viscosity increases
So, both behave in opposite ways.
Last verified on 19-05-2026
- Gas behaves ideally
- Repulsive forces dominate
- Attractive forces dominate
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Compressibility factor (Z) shows how real gas deviates from ideal gas behavior.
- If Z < 1, the gas is more compressible than expected.
- It means attractive forces between molecules are strong.
Last verified on 19-05-2026
تین ہاف لائف کے بعد مقدار کا کتنا حصہ باقی رہتا ہے؟
- 1/8
- 1/5
- 1/3
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- In radioactive decay or first-order reactions, each half-life reduces the amount to half.
- After every half-life, the remaining substance keeps dividing by 2.
- So after 3 half-lives, the remaining amount becomes (1/2)³ = 1/8.
Last verified on 19-05-2026
پہلے آرڈر ری ایکشن میں ہاف لائف کس چیز پر منحصر ہوتی ہے؟
- Depends on concentration
- Independent of concentration
- Directly proportional to concentration
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- In a first-order reaction, the half-life is constant.
- It does not depend on the initial concentration of the reactant.
- So, even if concentration changes, half-life remains the same.
Last verified on 19-05-2026