Chemistry Questions for Railway & SSC CGL Exam 2018: 7th June(With Video Solution)

Dear Students,

Railway Board offers opulent and revered job posts to its aspirants. And it is not every year that we get the notification from Railway offering a good number of vacant seats to the multitude aspirants. But the current year 2018 brought a pleasant surprise with almost 90,000 seats to be filled by the valid candidates. Opportunity is here but you have to welcome it with a provident strategy. The exam will be conducted in the month of May 2018. 

रेलवे बोर्ड अपने उम्मीदवारों के लिए भव्य और प्रतिष्ठित कार्य पदों की पेशकश करता है. और हर साल ऐसा नहीं होता है कि हमें रेलवे की ओर से अधिसूचना मिलती है. लेकिन वर्तमान वर्ष 2018 आपके लिए बहुत सुखद वर्ष है क्योंकि इसमें लगभग 90,000 सीटों को वैध उम्मीदवारों द्वारा भरा जाएगा. आपके पास बहुत अच्छा अवसर है और आपको इसे एक बेहतर रणनीति से प्राप्त करना होगा. परीक्षा मई 2018 के महीने में आयोजित की जायेगी.

Q1. Which gas known as ‘noble gas’? 
'नोबल गैस' किसे कहा जाता है?
(a) Hydrogen / हाइड्रोजन
(b) Oxygen / ऑक्सीजन
(c) Helium / हीलियम
(d) Carbon dioxide /कार्बन डाइआक्साइड
Show Answer
Sol. The noble gases make a group of chemical elements with similar properties under standard conditions, they are all odourless, colourless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are Helium (He), Neon (Ne), Argon (Ar), Krypton (Kr), Xenon (Xe) and the radioactive Radon (Rn). 

Q2. Percentage amount (by volume) of which one of the following gas is lowest in the atmosphere?
निम्नलिखित में से कौन सी एक गैस की प्रतिशत मात्रा (मात्रा से) वायुमंडल में सबसे कम है?
(a) Argon / आर्गन
(b) Carbon dioxide / कार्बन डाइऑक्साइड
(c) Nitrogen / नाइट्रोजन
(d) Oxygen / ऑक्सीजन
Show Answer
Sol. The atmosphere contains many gases mostly in a small amount including some pollutants and greenhouse gases. The most abundant gas in the atmosphere (by volume) is Nitrogen 78% with Oxygen second 20.95%, Argon 0.93% an inert gas is the third most abundant gas in the atmosphere. While Carbon dioxide holds the last position with 0.03%. So it is lowest in the atmosphere.

Q3. Which gas is not in the gaseous cycle? 
गैसीय चक्र में कौन सी गैस नहीं है?
(a) N_2
(b) O_2
(c) Carbon / कार्बन
(d) H_2
Show Answer
Sol. Biogeochemical cycles can be classed as gaseous in which the reservoir is that air or the oceans (via evaporation) and sedimentary in which the reservoir is earth’s crust. Gaseous cycles include Nitrogen, Oxygen, Carbon and Water. Sedimentary cycles include Iron, Calcium, Phosphorus, Sulphur and other more earthbound elements. 

Q4. The gases employed for respiratory activities of divers are- 
गोताखोरों की श्वसन गतिविधियों के लिए प्रयुक्त गैस हैं-
(a) Oxygen and Nitrogen / ऑक्सीजन और नाइट्रोजन
(b) Oxygen and Helium / ऑक्सीजन और हीलियम
(c) Oxygen and Argon / ऑक्सीजन और आर्गन
(d) Oxygen and Neon / ऑक्सीजन और नियॉन
Show Answer
Sol. The deep sea divers carry cylinders which contain a mixture of Oxygen and Helium. The presence of Helium generates less airway resistance than air and thereby requires less mechanical energy to ventilate the lungs.

Q5. What is the shape of Sulphur hexafluoride molecule? 
सल्फर हेक्साफ्लोराइड अणु का आकार क्या है?
(a) Trigonal pyramid / त्रिकोणीय पिरामिड
(b) Octahedral / अष्टभुजाकार
(c) Planar / प्लानर
(d) Tetrahedral / चतुष्फलकीय
Show Answer
Sol. Sulphur hexafluoride (SF_6) is an inorganic, colourless, odourless and non-flammable compound. SF_6 has an octahedral shape. It has 12 electrons around the central Sulphur atom. This means there are six electron pairs arranged in an octahedral shape.

Q6. Easily soluble in water- 
पानी में आसानी से घुलनशील है- 
(a) Carbon/कार्बन
(b) Nitrogen/नाइट्रोजन
(c) Ammonia/अमोनिया
(d) Iodine/आयोडीन
Show Answer
Sol. Ammonia being a polar molecule dissolves readily in water. This is due to the Hydrogen atoms of Ammonia which are bonded with a highly electronegative Nitrogen and the Hydrogen atoms of water molecules which are bonded with the highly electronegative Oxygen atom. 

Q7. Which is used as Laughing gas is- 
हास्य गैस (लाफिंग गैस) के रूप में उपयोग की जाने वाली गैस है- 
(a) Nitrous Oxide / नाईट्रस ऑक्साइड
(b) Nitrogen dioxide / नाइट्रोजन डाइऑक्साइड
(c) Nitrogen Trioxide / नाइट्रोजन ट्रायऑक्साइड
(d) Nitrogen Tetra Oxide / नाइट्रोजन टेट्राऑक्साइड
Show Answer
Sol. Nitrous Oxide (N_2 O) is also known as laughing gas. It is a colourless gas with a sweet odour and taste. Inhalation leads to disorientation, euphoria, numbness, loss of coordination, dizziness and ultimately a loss of consciousness. It is also used as the anesthetic gas. 

Q8. Which one of the following is also called Stranger Gas? 
निम्नलिखित में से किसे अजनबी गैस भी कहा जाता है? 
(a) Argon / आर्गन
(b) Neon / नीयन
(c) Xenon / क्सीनन
(d) Nitrous Oxide / नाइट्रस ऑक्साइड
Show Answer
Sol. Xenon is a chemical gas with symbol Xe and atomic number 54. It is a rare, odourless, colourless, tasteless, chemically unreactive gas. Xenon gas is also known as stranger gas as its volume is low in the atmosphere (0.08 parts per million of xenon). It was discovered in England by the Scottish chemist William Ramsay and British chemist Morris Travers in 1898. 

Q9. The gas used to inflate the tyres of an aircraft is- 
एक विमान के टायर में हवा भरने के लिए कौन सी गैस का प्रयोग किया जाता है? 
(a) Hydrogen / हाइड्रोजन
(b) Nitrogen / नाइट्रोजन
(c) Helium /हीलियम
(d) Neon / नीयन
Show Answer
Sol. Nitrogen gas is used in the tyres of an Aeroplane. This is because the nitrogen gas does not support combustion and can assist in preventing wheel fire when the aircraft lands (braking and high speed can produce dangerously high temperatures) unlike in oxygen. There are other benefits but effectively it is being the lowest cost gas that does not support combustion. It is preferred in comparison with the oxygen because nitrogen does not contain water. Thus, when the plane is at more height, gas in tyres does not get frozen.

Q10. The soil in which insectivorous plants grow is deficient in:
जिस मिट्टी में कीटाणुनाशक पौधे उगते हैं, उनमें ________की कमी होती है.
(a) Magnesium / मैग्नीशियम
(b) Calcium / कैल्शियम
(c) Nitrogen / नाइट्रोजन
(d) Water / जल
Show Answer
Sol. Insectivorous plants cannot take their nitrogen from soil as they grow in waterlogged swampy soils deficient in nitrogenous compounds. Such plants obtain their nitrogen from small insects. For this work, these plants have evolved special mode of nutritions. Example of insectivorous plants are Nepenthes, Dionea, Drosera, Utricularia, etc.

Q11. Which gas is usually filled in the balloon? 
गुब्बारों में आमतौर पर कौन सी हवा भरी जाती है?
(a) Hydrogen  / हाइड्रोजन
(b) Oxygen  / ऑक्सीजन
(c) Carbon dioxide / कार्बन डाइआक्साइड
(d) Helium  / हीलियम
Show Answer
Sol. A gas balloon flies in the air because it is filled with a gas which is lighter than air. Helium is mostly used in gas balloons. 

Q12. Tear gas is : 
आंसू गैस है:   
(a) Ammonia / अमोनिया
(b) Chlorine /क्लोरीन
(c) Hydrogen Carbide / हाइड्रोजन कार्बाइड
(d) Hydrogen sulphide / हाइड्रोजन सल्फ़ाइड
Show Answer
Sol. Tear gas is a chemical weapon that causes severe eye respiratory and skin burning, pain, vomiting and even blindness. It is mostly used by the police force in controlling nots. Alpha chloro acetophenol and acrolein are used as tear gas. Ammonia (NH3) is also used in tear gases.

Q13. Which of the following remains in a solid state at normal temperature? 
निम्नलिखित में से कौन सा सामान्य तापमान पर ठोस स्थिति में रहता है?
(a) Fluorine / फ़्लोरिन
(b) Chlorine /क्लोरिन
(c) Iodine / आयोडीन
(d)Bromine /ब्रोमिन 
Show Answer
Sol. The Group Seven (7) elements are also known as the Halogens. They include Fluorine, Chlorine, Bromine and Iodine which all have 7 electrons in their outer shell. Iodine is a bluish-black solid with a metallic lustre, thus it remains in a solid state at normal temperature. 

Q14. The most reactive among the Halogens is- 
हैलोजन में से सबसे अधिक प्रतिक्रियाशील है-
(a) Fluorine / फ़्लोरिन
(b) Chlorine / क्लोरिन
(c) Bromine / ब्रोमिन
(d) Iodine / आयोडीन
Show Answer
Sol. The Halogens (Fluorine, Chlorine, Bromine, Iodine, Astatine) are non-metal elements which are highly electronegative and reactive. Fluorine is the smallest atom of the halogen elements. It also has the strongest ability to attract electrons from other elements making it the most reactive of the halogens.

Q15. Which of the following is not optically active? 
इनमें से कौन सा ऑप्टिकल सक्रिय नहीं है?
(a) Glycine  / ग्लाइसिन
(b) Alanine  / ऐलेनाइन
(c) Serine / सेरीन
(d) All of the above  / उपरोक्त सभी
Show Answer
Sol. Glycine is a non-essential, non-optical amino acid. It is also known as a building block for protein. Its formula is NH_2 CH_2 COOH. An optically active compound should have at least one carbon atom attached to four different groups. Glycine is not active because the carbon atom is attached to 2 hydrogen atoms, 1 amino group and 1 carboxylic group. 

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