HEAT:
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 months of May 2018.
Q1.The temperature is measured with
तापमान किसके द्वारा मापा जाता है
(a)Altimeter/अल्टीमीटर
(b) Pyrometer / पाइरोमीटर
(c) Ammeter/ एम्मिटर
(d) Callipers/ कैलिपरस
Sol. Pyrometer is an instrument for measuring high temperatures, especially in furnaces and kilns.
Q2. Photovoltaic cells are ?
फोटोवोल्टाइक सेल क्या हैं
(a) Solar cells / सौर सेल
(b) Thermal cells / तापीय सेल
(c) Sulphur cells / सल्फर सेल
(d) Molar cells/ मोलर सेल
Sol. The conversion of light energy into electrical energy is based on the phenomenon called photov
oltaic effect. A photovoltaic cell is the basic unit of the system where the photovoltaic effect is utilized to produce electricity from light energy. Silicon is most widely used semiconductor material for construction photovoltaic cell.
Q3. When the door of refrigerator is opened in a closed room, then:
जब एक बंद कमरे में फ्रिज का दरवाजा खोला जाता है, तो:
(a) Immediately room become cooler/ अचानक कमरा ठंडा हो जाता है
(b) the temperature of room falls gradually/ कमरे का तापमान धीरे-धीरे गिरता है
(c) the temperature of room is not affected / कमरे का तापमान प्रभावित नहीं होता
(d) the room becomes hotter gradually/ कमरा धीरे-धीरे गर्म हो जाता है
Sol. The reason is that with the door open the temperature will start to rise inside the refrigerator. The thermostat will kick in and try to cool it back down. This means the motor is running which means heat is being added to the room.
Q4.The S.I unit of latent heat is
गुप्त ऊष्मा की एसआई इकाई क्या है-
(a) cal-g
(b) cal/°C
(c) joule /kg- जूल/किग्रा
(d) none of these/इनमे से कोई नहीं
Sol. The SI unit of latent heat is joule per kilogram
Q5. Minus 40 degree centigrade is equal to __ degree Fahrenheit.
न्यूनतम 40 डिग्री सेंटीग्रेड __ डिग्री फ़ारेनहाइट के बराबर है.
(a) 104
(b) 122
(c) – 40
(d) None of these/इनमे से कोई नहीं
Sol. Minus 40 degree centigrade is equal to -40 degree Fahrenheit.
-40°C×9/5+32
= -40°F
Q6. The safest temperature for keeping food fresh in a refrigerator is
एक रेफ्रिजरेटर में खाना ताजा रखने के लिए सबसे सुरक्षित तापमान कितना है
(a) 0°C – 4°C
(b) 8°C – 12°C
(c) 20°C – 25°C
(d) 10°C -15°C
Sol. The lower temperature slows the growth of microorganisms already in the food. According to international standards safest temperature for keeping food fresh in a refrigerator is 0°C – 4°C.
Q7. Why does food cook faster in a pressure cooker?
प्रेशर कुकर में खाना जल्दी पकाया जा सकता है ऐसा क्यों –
(a) The increased pressure increases the boiling point. / बढ़ता दबाव उबलते बिंदु को बढ़ाता है
(b) Does not waste steam. / भाप बर्बाद नहीं करता है
(c) The food is cooked quickly by steam. / भोजन भाप द्वारा जल्दी पकता है
(d) The water boils at constant temperature. / पानी लगातार एक ही तापमान पर उबलता है
Sol. The pressure inside the pressure cooker is very high. This raises the boiling point of water and the temperature inside the cooker is higher them 100°C which results in faster cooking of food.
Q8. A body floats at 4°C water. If temperature reaches 100°C then-
शरीर 4 डिग्री सेल्सियस पानी में तैरता है। यदि तापमान 100 डिग्री सेल्सियस तक पहुंच जाता है तो-
(a) The body will sink/शरीर डूब जाएगा
(b) No change/कोई परिवर्तन नहीं होगा
(c) More part of the body will submerge/शरीर का अधिक हिस्सा डूब जाएगा
(d) The body will float freely/शरीर स्वतंत्र रूप से तैरेगा
Sol. When the water is heated, its density decreases. The density of the water at 100°C is at the lowest, so the body will sink. Water density is maximum at 4°C, so the body will float.
Q9. Pure water freezes at what temperature?
शुद्ध पानी किस तापमान पर जम जाता है?
(a) 47 F
(b) 32 F
(c) 0 F
(d) 19 F
Sol. Water freezes at 32 degrees Fahrenheit or 0 degrees Celsius.
Q10. Xeric condition refers to-
ज़ैरिक स्थिति का संदर्भ है
(a) low temperature/कम तापमान
(b) Inadequate supply of water / पानी की अपर्याप्त आपूर्ति
(c) high evaporation/उच्च वाष्पीकरण
(d) extreme temperature/अधिकतम तापमान
Sol. Xeric denoting conditions characterized by an inadequate supply of water. Xeric conditions exist in arid habitats, extremely cold habitats, and in salt marshes.
Q11.The temperature of the filament of lighted electric bulb is generally:
रोशनी वाले बल्ब के फिलामेंट आम तौर तापमान कितना होता है
(a) 100°C to 500°C
(b) 1000°C to 1500°C
(c) 2500°C to 3000°C
(d) 4000°C to 5000°C
Sol. Tungsten metal is used as filament in electric bulb. When electric current flows through it, its temperature goes up to 2500°C from 3000°C. Generally, electric bulbs convert only 5% to 10% of electric energy to light.
Q12. The conductivity of a semi-conductor at zero degree Kelvin is-
शून्य डिग्री केल्विन में एक अर्धचालक की प्रवाहकत्त्व कितनी होगी-
(a) 10^5 ohm / ओम
(b) 10^(-1) ohm / ओम
(c) 10^(-5) ohm / ओम
(d) zero /शून्य
Sol.The materials [Germanium, Silicon] whose electrical conductivity varies between conductors and dielectric are called semiconductors. At absolute zero temperature, a semiconductor behaves like a perfect dielectric.
एक सुपर कंडक्टर द्वारा प्राप्त उच्चतम तापमान है –
(a) 24 K
(b) 138 K
(c) 150 K
(d) 300 K
Sol. Where as ordinary or metallic super conductors usually have transition temperature (temperature below which they are super conductive) below 30k and must be cooled using liquid helium in order to achieve super conductivity. High temperature super conductors have been observed with transition temperature as high as 138 K.
Q14.The resistance of a semiconductor on heating
हीटिंग पर अर्धचालक का प्रतिरोध:
(a) Remains/एक ही रहता है
(b) Decreases/कम होता है
(c) Increases/बढ़ता है
(d) None of the above/उपरोक्त में से कोई नहीं
Sol. With the increase in temperature, the conductivity of the semi-conductor material increases and resistance decreases.
Q15. What is absolute zero temperature?
निरपेक्ष शून्य तापमान क्या है?
(a) The starting point of any temperature scale/किसी भी तापमान का प्रारंभिक बिंदु
(b) No more heat can be removed (कोई अन्य उष्मा हटायी नहीं जा सकती है
(c) The temperature at which the vapour of any liquid substance is condensed(तापमान जिस पर किसी भी तरल पदार्थ की वाष्प घनी होती है
(d) The temperature at which all material are in vapour form.(तापमान जिस पर सभी पदार्थ वाष्प रूप में होते हैं.
Sol. Absolute zero is defined as the point where no more heat can be removed from a system, according to the absolute or thermodynamic temperature scale. This corresponds to 0 K or -273.15°C.
You may also like to read:
