Practical Viva — Common Questions Physics, Chemistry & Biology

Metre bridge kis principle pe kaam karta hai?

Wheatstone bridge ke principle pe — jab bridge balanced hota hai, galvanometer me current zero flow karta hai.

Balance point ko jitna possible ho, bridge ke centre (50 cm) ke paas kyun rakhte hain?

Kyunki wahan percentage error sabse kam hota hai — end points ke paas chhota measurement error bhi bada % error deta hai.

Jockey ko baar-baar rub kyun nahi karte wire pe?

Isse metre bridge wire ka uniform cross-section damage ho sakta hai, jo result galat kar dega.

Kya hoga agar galvanometer me deflection ek hi side dikhaye har jagah?

Iska matlab hai circuit me connection loose hai ya resistance box me koi resistance nahi lagaya — check karo.

Figure of merit kya hota hai?

Wo current jo galvanometer ki coil se pass karke scale pe ek division ka deflection produce kare.

Half-deflection method me shunt resistance kyun lagate hain?

Current ko half karne ke liye — taki galvanometer resistance calculate kiya ja sake without damaging it.

Galvanometer ko voltmeter/ammeter me kaise convert karte hain?

Voltmeter banane ke liye high resistance series me; ammeter banane ke liye low resistance (shunt) parallel me lagate hain.

Potentiometer, voltmeter se better kyun hai emf measure karne ke liye?

Balance point pe potentiometer se koi current draw nahi hota circuit se, isliye accurate emf milta hai — voltmeter kuch current leta hai.

Null point kya hota hai?

Wo point jahan galvanometer me zero deflection aata hai — matlab dono potential differences balance ho gaye.

Potential gradient kya hai?

Potentiometer wire ke per unit length pe potential drop.

Titration me end point kaise pehchante hain?

Indicator ke colour change se — jaise phenolphthalein colourless se pink ho jata hai.

Burette ko titrant se rinse karna kyun zaroori hai pehle?

Taki burette me pehle se present paani titrant ko dilute na kare aur reading galat na aaye.

Pipette aur burette ka use kaise alag hai?

Pipette ek fixed volume measure karta hai (transfer ke liye), burette variable volume deliver karta hai (drop by drop, titration ke liye).

Salt analysis me pehla step kya hota hai?

Physical examination — colour, smell, aur solubility dekh ke cation/anion ka rough idea lete hain.

Dilute HCl test kis group ke cations ke liye use hota hai?

Group I cations (Pb²⁺, Ag⁺, Hg₂²⁺) ke liye — ye insoluble chlorides bante hain.

Flame test kyun karte hain?

Kuch cations (jaise Na⁺, K⁺, Ca²⁺) flame ko characteristic colour dete hain, jisse unki quick identification ho jaati hai.

Rate of reaction temperature badhne se kyun badhta hai?

Molecules ki kinetic energy badhti hai, effective collisions zyada hote hain — Arrhenius equation isse explain karta hai.

Catalyst reaction rate kaise badhata hai?

Activation energy kam karke — reaction ka alternate, lower-energy pathway provide karke.

Spotting exam me sabse zyada kya dekha jata hai?

Identification (naam), classification/scientific name, aur ek-do distinguishing features likhne hote hain.

Onion peel slide me kya identify karna hota hai?

Plant cell ki structure — cell wall, nucleus, cytoplasm clearly labelled honi chahiye.

Pollen germination test kis liye kiya jata hai?

Ye check karne ke liye ki pollen grains viable (fertile) hain ya nahi — sucrose solution me germinate karke dekhte hain.

Pollen tube kya hota hai?

Germination ke baad pollen grain se nikalne wali tube jo style ke through ovule tak pahunchti hai fertilization ke liye.

Quadrat method kis liye use hota hai?

Ek defined area me plant population density aur frequency measure karne ke liye.

Population density kaise calculate karte hain?

Total number of individuals ÷ area (ya quadrats ki total sampled area).