SENIOR ELEMENTARY TEACHER SET PAST PAPERS AND SYLLABUS
چار آپشن میں سے کسی ایک پر کلک کرنے سے جواب سرخ ہو جائے گا۔
مینڈل کا آزادانہ درجہ بندی کا قانون کب لاگو ہوتا ہے؟
- On same chromosome and close together
- On different chromosomes or far apart on the same chromosome
- Always linked genes
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Mendel’s law of independent assortment explains how traits are inherited independently.
- It works during gamete formation (meiosis).
- Genes are inherited independently if they are not physically linked.
- This usually happens when genes are on different chromosomes.
- It can also apply when genes are far apart on the same chromosome (due to crossing over).
Last verified on 20-05-2026
کاپر کے مرکبات کا نیلا رنگ کس وجہ سے ہوتا ہے؟
- Metallic bonding
- Charge transfer
- d–d transition
- None of these
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Explanation
- Transition metal compounds show color due to electronic transitions.
- In copper compounds (especially Cu²⁺), d-orbitals are partially filled.
- Electrons absorb specific wavelengths of light and get excited between d-orbitals.
- The remaining reflected/transmitted light appears blue.
- This phenomenon is called d–d transition.
Last verified on 20-05-2026
- Secondary alkyl halide
- Primary alkyl halide
- Methyl bromide
- None of these
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Explanation
- SN2 reaction occurs in one step via backside attack.
- Steric hindrance strongly affects reaction rate.
- Less crowded substrates allow easier nucleophilic attack.
- Methyl halides have no alkyl groups blocking the carbon center.
- So they react the fastest in SN2 mechanism.
Last verified on 20-05-2026
ہیس کے قانون کے مطابق اینتھالپی کیوں حساب کی جا سکتی ہے؟
- State function
- Path function
- Intensive property
- None of these
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Explanation
- Hess’s law states that total enthalpy change is independent of path.
- It depends only on initial and final states of a reaction.
- This is possible because enthalpy does not depend on the route taken.
- Such properties are called state functions.
- Therefore, enthalpy follows path independence.
Last verified on 20-05-2026
پروپین کی اوزونولائسز سے کون سی مصنوعات بنتی ہیں؟
- Ethanol and methanol
- Ethanal and methanal
- Ethanoic acid and methanoic acid
- None of these
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Explanation
- Ozonolysis breaks the double bond of alkenes using ozone (O₃).
- Propene has structure: CH₃–CH=CH₂.
- Double bond cleavage forms two carbonyl compounds.
- One side gives ethanal (CH₃CHO) and the other gives methanal (HCHO).
- Therefore, these are the final products after ozonolysis.
Last verified on 20-05-2026
الکائل بینزین کو بینزوئک ایسڈ میں تبدیل کرنے کے لیے کیا استعمال ہوتا ہے؟
- NaOH
- KMnO₄, acidified
- H₂/Ni
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Alkyl benzene undergoes side-chain oxidation to form benzoic acid.
- A strong oxidizing agent is required for this conversion.
- Potassium permanganate (KMnO₄) in acidic medium is commonly used.
- It converts the alkyl side chain completely into –COOH group.
- Example: Toluene → Benzoic acid.
Last verified on 20-05-2026
گیبریل فثالیمائڈ سنتھیسس کس کے لیے استعمال ہوتا ہے؟
- 1° amine
- 2° amine
- 3° amine
- None of these
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Explanation
- Gabriel phthalimide synthesis is a method to prepare amines.
- It involves alkylation of phthalimide followed by hydrolysis.
- This method specifically gives only primary amines.
- It avoids formation of secondary and tertiary amines.
- Therefore, it is a selective and controlled preparation method.
Last verified on 20-05-2026
- r = [A]¹[B]²
- r = [A]²[B]¹
- r = [A]²[B]⁰
- None of these
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Explanation
- Rate law shows how reaction rate depends on reactant concentrations.
- If rate does NOT change when B changes, then B has no effect on rate.
- This means the order of reaction with respect to B is zero.
- So B appears with exponent 0 in the rate law.
- Therefore, rate depends only on A.
Last verified on 20-05-2026
نائٹرو بینزین کو اینیلین میں تبدیل کرنے کے لیے کون سا ری ایجنٹ استعمال ہوتا ہے؟
- H₂/Ni
- Fe/HCl
- KMnO₄
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Nitrobenzene (C₆H₅NO₂) is reduced to aniline (C₆H₅NH₂).
- Reduction requires removal of oxygen and addition of hydrogen.
- Common lab method uses metals in acidic medium.
- Iron (Fe) with hydrochloric acid (HCl) is widely used (Béchamp reduction).
- It efficiently converts nitro group (–NO₂) to amino group (–NH₂).
Last verified on 20-05-2026
اینڈوتھرمک ری ایکشن کب خود بخود ہوتا ہے؟
- ΔG = +ve
- ΔG = 0
- ΔG = −ve
- None of these
اس سوال کو وضاحت کے ساتھ پڑھیں
Explanation
- Spontaneity of any reaction depends on Gibbs free energy (ΔG).
- Endothermic reaction absorbs heat, but can still be spontaneous.
- The key condition for spontaneity is that free energy must decrease.
- This happens when system moves to a more stable state.
- So ΔG must be negative.
Last verified on 20-05-2026
