224. Detergents dissolved in water help in cleaning clothes by :
       (a) increasing the temperature of water
       (b) reacting chemically with dirt
       (c) reducing the surface tension of water"
       (d) dissolving dirt
Ans : (c)
225. A boat loaded with rocks floats in the middle of a swimming pool and a man in the boat throws rocks over board in water. The
     water level of the pool will :
       (a) rise
       (b) be lowered
       (c) remain unchanged
       (d) first rises then goes down
Ans : (b)
226. If a pendulum clock be taken from the earth to a revolving artificial satellite, it will : [IAS 2003]
       (a) run slow
       (b) run fast
       (c) give the same time"
       (d) stop altogether
Ans : (d)
227. A remote control gadget (for TV etc.) has in it:
       (a) a small electromagnet, that emits electromagnetic waves
       (b) a small oscillator that emits electric pulses
       (c) a small transmitter that emits infrared signals
       (d) None of the above
Ans : (c)
228. In, storms, the roofs of some houses are carried away. This is in accordance with:
       (a) Bernoulli"s principle
       (b) Archimedes" principle
       (c) Law of inertia
       (d) Pascal"s law
Ans : (a)
229. In Newton"s third law, the action and reaction forces:
            1) act on different bodies.
            2) act on the same body.
            3) are not always equal.
            4) are always equal.
           Choose the correct answer from the codes given below:
       (a)  1 and 3
       (b)  1 and 4
       (c)  2 and 4
       (d)  2 and 3
Ans : (b)
230. A rocket and a jet engine differ because:
           A. their working principles are entirely different.