Option “3” is correct. Farsightedness (Hypermetropia) as it is medically termed is a vision condition in which distant object are usually seen clearly, but close ones do not come into proper focus. To remove this vision problem one should use a convex lens.
262. Meter in a vehicle that calculates distance covered by the vehicle is called __________.
1. Speedometer
2. Odometer
3. Thermometer
4. Kilometre
Option “2” is correct. An odometer or odograph is an instrument for measuring the distance travelled by a vehicle, such as a bicycle or car. The device may be electronic, mechanical, or a combination of the two.
Option “3” is correct. When the ice melts to liquid water, the structure collapses and the density of the liquid increases. At temperatures well above freezing, the molecules move faster and get further apart. The density decreases as temperature increases thus, the density of water is a maximum at 4 °C.
264. Which of the following is not a vector quantity?
1. Work done
2. Force
3. Displacement
4. Velocity
Option “1” is correct. Work done due to displacement caused by a force is a scalar quantity.
265. Terminal velocity ___________.
1. first increases before decreasing
2. is constant
3. first decreases before increasing
4. always keeps on increasing
Option “2” is correct. Terminal velocity is the constant speed that a freely falling object eventually reaches when the resistance of the medium through which it is falling prevents further acceleration.
266. What is the SI unit of pressure?
1. Newton
2. Weber
3. Pascal
4. Henry
Option “3” is correct. The SI unit for pressure is the pascal (Pa), equal to one newton per square metre (N/m2, or kg•m−1•s−2). This name for the unit was added in 1971. It is named after the French polymath Blaise Pascal.
267. How can we measure specific gravity of milk?
1. Using a viscometer
2. Using an odometer
3. Using a hygrometer
4. Using a hydrometer
Option “4” is correct. A hydrometer is an instrument used to measure the specific gravity (or relative density) of liquids. It is also used to measure specific gravity of milk.
268. Who invented the nuclear reactor?
1. Enrico Fermi
2. Adolf Gaston Eugen Fick
3. Sandford Fleming
4. Benoit Fourneyron
Option “1” is correct. Enrico Fermi was an Italian-American physicist and the creator of the world’s first nuclear reactor, the Chicago Pile-1. He has been called the “architect of the nuclear age” and the “architect of the atomic bomb”.
269. Which among the following in false about work?
1. If displacement is zero, work is zero
2. Work done can be negative
3. It is a vector quantity
4. Its unit is Joule
Option “3” is correct. Whenever a force is applied to an object, causing the object to move, work is done by the force. Work done due to displacement caused by a force is a scalar quantity. Work can be either positive or negative.The unit of work is the unit of energy, the joule (J). 1 J = 1 N m.
270. Reflection from a smooth surface like that of a mirror is called ___________ reflection.
1. Regular
2. Irregular
3. Diffused
4. Fused
Option “1” is correct. When a beam pass of parallel light rays is incident on a smooth and plane surface, the reflected rays will also be parallel. This type of reflection is called Regular Reflection.
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