# RRB JE Exam: Chemistry (Atomic Structure) Quiz | 6th March

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Q1. The absolute value of charge on electron was determined by
इलेक्ट्रॉन पर आवेश का निरपेक्ष मान किस के द्वारा निर्धारित किया गया था?
(a) J.J. Thomson / जे.जे. थॉमसन
(b) R.A. Millikan/ आर. ए. मिलिकन
(c) Rutherford / रदरफोर्ड

Ans (b)
Sol. Robert Andrews Millikan was an American experimental physicist honored with the Nobel Prize for Physics in 1923 for the measurement of the elementary electric charge and for his work on the photoelectric effect.

Q2. The charge on positron is equal to the charge on–
पॉज़िट्रॉन पर चार्ज, ________ पर चार्ज के बराबर है
(a) proton/प्रोटोन
(b) electron/इलेक्ट्रान
(c) α –particle/ α- कण
(d) neutron/न्यूट्रॉन

Ans (a)
Sol. The charge on positron is equal to the charge on proton.

Q3. The value of planck’ constant is–
प्लैंक कांस्टेंट का मान क्या है?
(a) 6.62×〖10〗^(-34)J
(b) 6.62×〖10〗^(-34)J.s
(c) 6.62×〖10〗^(-34)erg. s
(d) none of these/ इनमें से कोई नहीं

Ans (b)
Sol. Planck’s constant, symbolized h, relates the energy in one quantum (photon) of electromagnetic radiation to the frequency of that radiation. In the International System of units (SI), the constant is equal to approximately 6.626176 x 10-34 joule-seconds.

Q4. In a given atom, no two electrons can have the same value for all the four quantum number. This is called–
किसी दिए गए परमाणु में, किसी भी दो इलेक्ट्रॉनों में सभी चार क्वांटम संख्या के लिए समान मूल्य नहीं हो सकता है. इसे क्या कहा जाता है?
(a) Hund’s rule / हुंड का नियम
(b) Pauli’s exclusion principle/ पाउली का अपवर्जन का नियम
(c) uncertainty principle/ अनिश्चितता का सिद्धांत
(d) Aufbau’s principle/ आफबाऊ का सिद्धांत

Ans (b)
Sol. The Pauli Exclusion Principle states that, in an atom or molecule, no two electrons can have the same four electronic quantum numbers. As an orbital can contain a maximum of only two electrons, the two electrons must have opposing spins.

Q5. The atomic orbital is–
परमाणु कक्षीय क्या है?
(a) the circular path of the electron/ इलेक्ट्रॉन का गोलाकार मार्ग
(b) elliptical shaped orbit/ अण्डाकार आकार की कक्षा
(c) three dimensional field around nucleus/ नाभिक के आसपास तीन आयामी क्षेत्र
(d) the region in which there is maximum probability of finding electron/ वह क्षेत्र जिसमें इलेक्ट्रॉन मिलने की अधिकतम संभावना है

Ans (d)
Sol. The particle moves in the form of a wave around the nucleus and at a certain point there is a definite probability of finding the electron. An atomic orbital is defined as the three-dimensional region of space around the nucleus within which the probability of finding the electron is maximum.

Q6. The maximum number of electrons on a principal shell is–
एक प्रमुख शेल पर इलेक्ट्रॉनों की अधिकतम संख्या कितनी है?
(a) n²
(b) n
(c) 2n²
(d) 3n²

Ans (c)
Sol. The maximum number of electrons on a principal shell is 2n².

Q7. Meson was discovered by–
मेसन का आविष्कार किस के द्वारा किया गया था?
(a) Yukawa/युकावा
(b) Seaburg/सीबर्ग
(c) Anderson/एंडरसन
(d) None of these/इनमें से कोई नहीं

Ans (a)
Sol. Predicted theoretically in 1935 by the Japanese physicist Yukawa Hideki, the existence of mesons was confirmed in 1947 by a team led by the English physicist Cecil Frank Powell with the discovery of the pi-meson (pion) in cosmic-ray particle interactions.

Q8. Which orbital is dum-bell shaped–
कौन सा कक्ष डम-बेल के आकार का होता है?
(a) s-orbital/ s- कक्ष
(b) p-orbital/ p- कक्ष
(c) d-orbital/ d- कक्ष
(d) f-orbital/ f- कक्ष

Ans (b)
Sol. S orbital (Spherical shape) 2 Page 3 P orbitals (Dumbbell shaped in three orientations) D orbitals: Dumbbell with a ring around it. As a consequence of Quantum Mechanics it turns out that bits of matter, such as electrons, obey what is called the Pauli exclusion principle.

Q9. The number of unpaired electrons in carbon atom is–
कार्बन परमाणु में अयुग्मित इलेक्ट्रॉन की संख्या कितनी है
(a) 2
(b) 4
(c) 1
(d) 3

Ans (a)
Sol. By Hund’s rule, the electron configuration of carbon, which is 1s 2 2s 2 2p 2, is understood to correspond to the orbital diagram shown in c. Experimentally, it is found that the ground state of a neutral carbon atom does indeed contain two unpaired electrons.

Q10. Tritium is an isotope of–
ट्रिटियम किस का समस्थानिक (आइसोटोप) है?
(a) Oxygen/ऑक्सीजन
(b) Hydrogen/हाइड्रोजन
(c) Phosphorus/फॉस्फोरस
(d) Nitrogen/नाइट्रोजन