1.
Water is heated in a kettle. Te inside water is heated by convection. A person sitting near the fire receives heat by :
Correct Answer
B. Convection
Explanation
When water is heated in a kettle, the inside water gets heated by convection. Convection is the transfer of heat through the movement of fluids or gases. In this case, as the water near the heat source gets heated, it becomes less dense and rises, while the cooler water from the top moves down to take its place. This creates a circular motion, known as convection currents, which helps in distributing the heat throughout the kettle. Thus, the person sitting near the fire receives heat through convection.
2.
A time can come when we will be able to design a machine which can go on working for ever without the expenditure of energy. Is it possible ?
Correct Answer
A. No
Explanation
The statement suggests that it is not possible to design a machine that can work forever without expending energy. This is in line with the laws of thermodynamics, specifically the first law which states that energy cannot be created or destroyed, only transferred or converted from one form to another. Therefore, any machine, no matter how advanced, would still require some form of energy input to function, making it impossible to work indefinitely without expending energy.
3.
The measurement of rainfall is made by an instrument known as
Correct Answer
D. Pedometer
4.
Light year is a unit of
Correct Answer
A. Distance
Explanation
A light year is a unit of distance. It is the distance that light travels in one year, approximately 9.46 trillion kilometers. It is used to measure vast distances in space, as the speed of light is the fastest known in the universe.
5.
Three elements needed for the healthy growth of plants are :
Correct Answer
A. N,P,K
Explanation
N, P, and K are the chemical symbols for the essential nutrients nitrogen, phosphorus, and potassium, respectively, which are required for the healthy growth of plants. These nutrients play crucial roles in various plant processes, such as photosynthesis, energy transfer, and the development of roots, flowers, and fruits. Therefore, the correct answer is N,P,K.
6.
Copper can be converted into gold by
Correct Answer
E. None of these
Explanation
Copper cannot be converted into gold by any of the given methods. Heating, artificial radioactivity, electroplating, and chemical reactions do not have the ability to change the atomic structure of an element and convert it into another element. The process of converting one element into another, such as turning copper into gold, would require nuclear reactions, which are not possible with the methods listed. Therefore, the correct answer is "None of these."
7.
In winter an iron pipe feel colder than a wooden window . This is because wood is :
Correct Answer
B. Non-Conductor
Explanation
Wood is a non-conductor of heat, while iron is a conductor of heat. In winter, when the temperature is cold, the iron pipe conducts the heat away from our body faster than the wooden window. This makes the iron pipe feel colder to the touch compared to the wooden window, even though they may be at the same temperature.
8.
The echo (reflected sound) will be distinctly heard only at ordinary temperatures if the distance of the reflecting surfaces from the source of sound is at least :
Correct Answer
A. 1120 ft
Explanation
The correct answer is 1120 ft. This is because sound travels at a speed of approximately 1120 feet per second in air. In order for an echo to be distinctly heard, the sound waves need enough time to travel to the reflecting surface and back to the source. If the distance is less than 1120 ft, the reflected sound waves will reach the source before the original sound waves have dissipated, resulting in overlapping and unclear echoes. Therefore, a distance of at least 1120 ft is needed for the echo to be distinctly heard.
9.
T is possible to recognize a person in the dark by simply hearing his unique voice . It is because of the
Correct Answer
A. Pitch
Explanation
The reason it is possible to recognize a person in the dark by simply hearing their unique voice is because of the pitch. Pitch refers to the perceived frequency of a sound, and each person's voice has a distinct pitch. This allows us to differentiate between different individuals based on their voice characteristics, even without visual cues.
10.
When a ray of sunlight enters a dark room , its straight path become visible because of dust particles hanging in the air. It is because light is :
Correct Answer
A. Visible
Explanation
When a ray of sunlight enters a dark room, its straight path becomes visible because of dust particles hanging in the air. These dust particles scatter the light, causing it to be visible to our eyes.
11.
A six feet tall lady wants to see her full image in a plane mirror . The minimum length of the mirror will be :
Correct Answer
A. 6 feet
Explanation
The minimum length of the mirror will be 6 feet because the lady is already six feet tall, so in order to see her full image, the mirror should be able to reflect her entire height.
12.
The principle used in radar is the same as that of Sonar. In radar we use radio waves ; whereas in sonar we use
Correct Answer
C. Ultrasonic
Explanation
The principle used in radar is the same as that of Sonar. Radar uses radio waves to detect and locate objects, while Sonar uses ultrasonic waves. Ultrasonic waves have a frequency higher than the upper limit of human hearing, making them ideal for underwater applications. Both radar and Sonar rely on the principle of emitting waves and measuring the time it takes for the waves to bounce back to determine the distance and location of objects. Therefore, ultrasonic is the correct answer as it accurately describes the principle used in Sonar.
13.
In a fission nuclear reaction , a heavy nucleus breaks up into smaller nuclei whereas in another nuclear reaction two or more than two possibly nuclei are fused to form a heavy nucleus This nuclear reaction is called :
Correct Answer
D. Fusion nuclear reaction
Explanation
In a fusion nuclear reaction, two or more than two nuclei are fused together to form a heavy nucleus. This is different from a fission nuclear reaction, where a heavy nucleus breaks up into smaller nuclei. Therefore, the correct answer is fusion nuclear reaction.
14.
Parsec is a unit of :
Correct Answer
D. Distance
Explanation
A parsec is a unit of distance used in astronomy to measure the vast distances between celestial objects. It is equal to approximately 3.26 light-years or about 31 trillion kilometers. Therefore, the correct answer is distance.
15.
German Silver is an alloy of:
Correct Answer
E. None of these
Explanation
German Silver is an alloy that is primarily composed of copper, zinc, and nickel. It does not contain tin (Sn) as mentioned in one of the options. Therefore, the correct answer is "None of these".
16.
The Continent Antarctica lies at the:
Correct Answer
B. South pole
Explanation
Antarctica lies at the South pole. This is because the South pole is the southernmost point on Earth, and Antarctica is located at the southernmost part of the planet. It is the coldest, driest, and windiest continent, covered mostly by ice. The North pole, on the other hand, is located in the Arctic region, which is covered by the Arctic Ocean. The middle of the Earth and the equator are not correct options as they do not accurately represent the location of Antarctica. Therefore, the correct answer is the South pole.
17.
The temperature of the dead body is:
Correct Answer
E. None of these
Explanation
When the body first dies it will retain its normal core body temperature (37o in humans) for about an hour before steadily loosing heat over time. Crime scene investigators use this to work out how long a body has been dead. They measure the core body temperature with a liver probe and for every degree below 37 they judge the body to have been dead for approxamaitly 1 hour.
18.
Lactometer is a type of Hydrometer which is used to measure the specific gravity of :
Correct Answer
C. Milk
Explanation
A lactometer is a type of hydrometer used specifically to measure the specific gravity of milk. The specific gravity of milk is an important parameter that indicates its density and composition. By measuring the specific gravity, the lactometer can determine the quality and authenticity of milk, as well as detect any adulteration or dilution. Therefore, the correct answer is milk.
19.
Cusec is a unit of :
Correct Answer
E. None of these
Explanation
cusec ( ) n. A volumetric unit for measuring the flow of liquids, equal to one cubic foot per second.
20.
The deepest place on earth is
Correct Answer
B. Mariana Trench
Explanation
The Mariana Trench is the deepest place on earth, reaching a depth of approximately 36,070 feet (10,994 meters). Located in the western Pacific Ocean, it is a crescent-shaped trench formed by the subduction of the Pacific tectonic plate beneath the Philippine Sea plate. The immense depth of the Mariana Trench is a result of this subduction process, making it the correct answer to the question.
21.
Winkling of stars is caused by
Correct Answer
C. Refraction of light
Explanation
The twinkling of stars is caused by the refraction of light. As starlight passes through the Earth's atmosphere, it encounters different layers of air with varying densities. This causes the light to bend or refract, resulting in the twinkling effect that we observe from the ground. The refraction of light is responsible for the apparent fluctuation in brightness and position of stars, giving them a twinkling appearance.
22.
Agnifying power of a simple microscope can be increased by
Correct Answer
A. Increasing focal length of the lens
Explanation
The magnifying power of a simple microscope can be increased by increasing the focal length of the lens. This is because the magnifying power of a lens is directly proportional to its focal length. By increasing the focal length, the lens is able to bend light rays at a greater angle, resulting in a larger magnification of the object being viewed.
23.
Bronze medal is made up of metal :
Correct Answer
C. Copper , Tin
Explanation
Bronze is an alloy made up of copper and tin. Copper provides the base metal, while tin is added to enhance the strength and hardness of the alloy. This combination of metals gives bronze its characteristic properties, such as corrosion resistance, durability, and a warm golden color. Copper and tin are commonly used together to create bronze due to their compatibility and the desirable qualities they impart to the alloy.
24.
One of the countries through which equator passes is
Correct Answer
A. Kenya
Explanation
The equator is an imaginary line that divides the Earth into Northern and Southern Hemispheres. Kenya is one of the countries through which the equator passes. This means that Kenya is located near the center of the Earth, experiencing a relatively warm climate throughout the year.
25.
A very important practical application of properties of matter is hoeing or "godi" practiced by the farmers. This property of matter is called :
Correct Answer
B. Capillarity
Explanation
Capillarity is the property of matter that allows liquids to flow against gravity in narrow spaces, such as the movement of water through the roots of plants. In the context of the given question, the practice of hoeing or "godi" by farmers involves the use of capillary action to transport water from a source to the plants. Therefore, capillarity is the correct answer as it describes the property of matter that is relevant to this practical application.
26.
It is observed that the total pressure exerted by air on the man of average siz is around 14.7 lb wt. per square inch. But the man feels quite comfortable,. It is because of :
Correct Answer
C. Of gravity
Explanation
The correct answer is "of gravity". The reason the man feels comfortable despite the pressure exerted by the air is because gravity pulls the man upward. Gravity counteracts the pressure exerted by the air, allowing the man to feel comfortable.