Q1. Force of attraction between the molecules of different substances is called
(a) Surface tension
(c) Adhesive force
(d) None of above
Q2. The safest temperature for keeping food fresh in a refrigerator is
Q3. Which instrument is used in submarine to see the objects above sea level ?
Q4. Why does food cook faster in a pressure cooker?
(a) The increased pressure increases the boiling point.
(b) Does not waste steam.
(c) The food is cooked quickly by steam.
(d) The water boils at constant temperature.
Q5. A biotechnique in which ultrasonic sound is used-
Q6. Television signals cannot be received beyond a certain distance because:
(a) Signals are weak
(b) Antenna is weak
(c) Air absorbs signals
(d) The surface of the earth is curved
Q7. The principle reason why it is better to have two eyes than one is that:
(a) By having two eyes we can distinguish colour easily
(b) By having two eyes we can easily see in the dark as well in dim light
(c) It gives a man a type of vision known as mosaic vision
(d) It enhances distance and depth perception in us
Q8. Which is not used as Atomic fuel?
Q9. The gas used in discharge tubes for optical decoration and advertising is-
(a) Carbon dioxide
(c) Sulphur dioxide
Q10. The Puckle gun was invented by–
(a) J.L. Beared
(b) G. Brousa
(c) Karl Benz
(d) James Puckle
Sol. Adhesive forces are the attractive forces between unlike molecules.
Sol. Refrigerator temperatures do not destroy pathogenic or spoilage microorganisms. The lower temperature slows the growth of microorganisms already in the food. According to international standards, the recommended temperature of the refrigerator is 36°F to 38°F (1.7°C to 3.3°C). Thus option (a) is correct.
Sol. A periscope is an instrument for observation over, around or through an object, obstacle or condition that prevents direct line-of-sight observation from an observer’s current position
Sol. The trapped steam increases the atmospheric pressure inside the cooker by 15 pounds per square inch (psi), or 15 pounds above normal sea-level pressure. At that pressure, the boiling point of water is increased from 212°F to 250°F. This higher temperature cooks food faster.
Sol. Sonography or ultrasonography is an important mean of clinical diagnosis. It is a diagnostic imaging technique based on the application of ultrasound. It is widely used in the field of medical science.
Sol. Television signals cannot be received beyond a certain distance because the surface of the earth is curved, due to this the signals moves further without hitting the earth’s surface.
Sol. Human beings have stereoscopic vision (stereopsis) means having eyes at the front of their head. The two eyes are a few centimeters apart from each other. Due to this, two eyes see the same object from two slightly different angles and send two slightly different images to the brain. The brain combines these two images to build a three-dimensional picture of the object and we can judge the depth and distance of the object more accurately.
Sol. The most common nuclear fuels are uranium – 235 (235U) and plutonium -239(239Pu). Thorium is more abundant in nature than uranium. Thorium can be used as a nuclear fuel through breeding to uranium-233 (U-233). Lead is not used as a nuclear fuel.
Sol. The neon gas is used in discharge lamps, tubes and in fluorescent bulbs.
Sol. In 1718 an Englishman named James Puckle was invented defence gun to be one of the keys steps in the evolution of mechanical machine guns.
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