# Physics [Heat] For ALP Stage-II Quiz Exam : 24th December 2018

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 1,27,278 seats to be filled by the valid candidates. Opportunity is here but you have to welcome it with a provident strategy.

Q1. If the doors of a refrigerator are left open for a few hours, the room temperature will
यदि रेफ्रिजरेटर के दरवाजे कुछ घंटों के लिए खुले छोड़ दिए जाते हैं, तो कमरे के तापमान में-
(a) decrease / कमी होगी
(b) increase / वृद्धि होगी
(c) remain the same / समान रहेगा
(d) decrease only in the area in the vicinity of the refrigerator/ केवल रेफ्रिजरेटर के आसपास के क्षेत्र में कमी आएगी

Ans.(b)
Sol. If the doors of a refrigerator are left open for a few hours, the room temperature will increase as heat is merely recycled from the room into the refrigerator and then back into the room. Thus, a net room temperature would increase from the heat of the motor that would be constantly running to move energy around in a circle.

Q2. Thermostat is a device which
थर्मोस्टेट एक उपकरण है जो-
(a) measures heat / ऊष्मा को मापता है
(b) measures temperature / तापमान को मापता है
(c) automatically regulates the temperature of a system / स्वचालित रूप से एक प्रणाली के तापमान को नियंत्रित करता है
(d) automatically regulates pressure of a system./ स्वचालित रूप से एक प्रणाली के दबाव को नियंत्रित करता है

Ans.(c)
Sol. Thermostat is a device which automatically regulates the temperature of a system. As the word suggests. Thermostat = Termo + stat i.e., keeping temperature (Thermo) Constant (static)

Q3. The cooling by a desert cooler is based on
एक रेगिस्तान कूलर द्वारा शीतलन किस पर आधारित है?
(a) hot air replacement / गर्म हवा प्रतिस्थापन
(b) air dehydration / वायु निर्जलीकरण
(c) evaporative cooling / वाष्पशील शीतलन
(d) air rehydration / वायु पुनर्जलीकरण

Ans.(a)
Sol. Desert coolers are based on the simple principle of hot air replacement where unsaturated air comes in contact with water leading to evaporation of water. In the process, the moisture content of air increases, while its temperature decreases. The resulting cold but moist air is used for providing cooling.

Q4. When water is heated from 0°C to 4°C, its volume
जब पानी 0 ° C से 4 ° C तक गर्म होता है, तो इसका आयतन-
(a) increases / बढ़ता है
(b) decreases / घट जाता है
(c) first increases then decreases / पहले बढ़ता है फिर घटता है
(d) remains the same / समान रहता है

Ans.(b)
Sol. When water is heated from 0°C to 4°C, its volume decreases. Density = Mass/Volume
Density of water is maximum at 4°C.

Q5. Heat detectors in human skin are sensitive to wavelengths
मानव त्वचा में हीट डिटेक्टर किस तरंग दैर्ध्य के प्रति संवेदनशील होते हैं?
(a) > 780 nm
(b) 600 – 780 nm
(c) 400 – 600 nm
(d) < 400 nm

Ans.(d)
Sol. Heat detectors in human skin are sensitive to wavelengths < 400 nm.

Q6. Food in the pressure cooker is cooked faster, as
प्रेशर कुकर में खाना तेजी से पक जाता है, क्योंकि उसमे-
(a) the boiling point increases due to an increase in pressure / दबाव में वृद्धि के कारण क्वथनांक बढ़ता है
(b) the boiling point decreases due to an increase in pressure / दबाव में वृद्धि के कारण क्वथनांक कम हो जाता है
(c) more steam is available at 100°C /100 ° C पर अधिक भाप उपलब्ध होती है
(d) more pressure is available at 100°C /100 ° C पर अधिक दबाव उपलब्ध होता है

Ans.(a)
Sol. The pressure cooker works on the principle of Gay-Lusaac’s Law which states that at constant volume, pressure is directly proportional to temperature. So when we heat the cooker, the inside temperature increases, thereby increasing the pressure and thus, cooking the food faster.

Q7. When water is heated from 0°C to 10°C, its volume
जब पानी 0 ° C से 10 ° C तक गर्म किया जाता है तो इसका आयतन-
(a) increases / बढ़ता है
(b) decreases / घटता है
(c) does not change / नहीं बदलता है
(d) first decreases and then increases / पहले घटता है और फिर बढ़ता है
Ans.(d)
Sol. When water is heated from 0°C to 10°C  then the volume of water first decreses and then increases. This is because water contracts on heating from 0°C to 4°C while expands from 4°C onwards.

Q8. Which zone of a candle flame is the hottest?
मोमबत्ती की लौ का कौन सा क्षेत्र सबसे गर्म है?
(a) Dark innermost zone / गाढ़ा अंतरतम क्षेत्र
(b) Outermost zone / बाहरी क्षेत्र
(c) Middle luminous zone / मध्य चमकदार क्षेत्र
(d) Central zone/ केंद्रीय क्षेत्र
Ans.(b)
Sol. There are several zones within a non-luminous flame with each zone having a different temperature. The outer most zone of the flame is blue in colour and it is hottest part. This is due to complete combustion. The middle zone is moderately not and yellow in colour as partial combustion occur in this zone while the innermost zone is the least not and black in colour due to presence of unburned wax vapours.

Q9. Evening Sun is not as hot as the mid day sun. What is the reason?
शाम का सूरज, दोपहर के सूरज के जितना गर्म नहीं होता है, इसका क्या कारण है?
(a) In the evening, radiation travel slowly / शाम में, विकिरण धीरे-धीरे यात्रा करती है
(b) In the evening, the temperature of the sun decreases / शाम के समय सूर्य का तापमान कम हो जाता है
(c) Ozone in atmosphere absorbs more light in the evening / वातावरण में ओजोन शाम के समय अधिक प्रकाश सोखती है
(d) In the evening, radiations travels larger distance through atmosphere / शाम के समय, विकिरण वायुमंडल के माध्यम से लम्बी दूरी की यात्रा करती है
Ans.(d)
Sol. In evening, the radiation from the sun travel larger distance through atmosphere that’s why evening sun is not as hot as the mid day sun.

Q10. A fan produces a feeling of comfort during hot weather, because
एक पंखा गर्म मौसम के दौरान आराम का अहसास करवाता है, क्योंकि-
(a) Our body radiates more heat in air / हमारा शरीर हवा में अधिक गर्मी फैलाता है
(b) fan supplies cool air / पंखा ठंडी हवा की आपूर्ति करता है
(c) conductivity of air increases / वायु की चालकता बढ़ जाती है
(d) our perspiration evaporates rapidly / हमारा पसीना तेजी से वाष्पित होता है
Ans.(d)
Sol. A fan produces a feeling of comfort during hog weather because our perspiration evaporates rapidly.

You may also like to read:

×

Thank You, Your details have been submitted we will get back to you.

×
OR

×