Sunday, March 15, 2015

Sure shoot MCQ for class 9 science term-2

Q. Four students observed the specimens of two plants and sketched them as shown below. They noted in their notebook the identification and the names of the group to which these plants belong

(a) A – moss ; Bryophyta B – fern ; Pteridophyta
(b) A – pine ; Gymnosperm B – leafy plant ; Angiosperm 
(c) Both A and B are moss and belong to Bryophyta 
(d) Both A and B are ferns and belong to Pteridophyta.

Ans: (a) A – moss ; Bryophyta B – fern ; Pteridophyta

Q. A strong transverse horizontal pulse, created at one end of a string, is observed to complete 5 journeys along its length, before fading out. The initial reading of the stop clock used in the experiment was 5 s and the final reading was 55 s. If the length of the string for one journey is L metre, the speed of the pulse, through the string is :

(a) (L/55) ms21 (b) (L/50) ms21 (c) (L/11) ms21 (d) (L/10) ms21

Ans: (d) (L/10) ms21

Q. To determine the speed of a pulse through a stretched string a student can choose

Ans: Thick cotton string and A stop clock

The cotton string is a better carrier of the pulse while the stop clock enables us to measure time more accurately.

Q. Which in your opinion is more basic characteristics for classifying organism – the place where they live in or the kind of cells they are made of ?

Ans: The kind of cells the organisms are made of

Q. The wave property of sound which does not affect the hearing process is:

(a) Intensity (b) loudness (c) velocity of sound (d) amplitude

Ans: (a) Intensity

3. A strong transverse pulse is created at one end of a string. It completes 10 journeys along its length, before fading out. The initial reading of the stop clock used in the experiment was 25s and the final reading was 75s. If the length of the string for one journey is L meter, the speed of the pulse, through the string is

(a) L/75ms (b) L/5ms (c) L/25ms (d) L/10ms

Ans: The time taken for one journey is (75- 25)/10 second. = 5se

The speed of the pulse is (b) L/5ms

Q. What precaution should be taken for experiment on measuring the speed of a pulse through a string

Ans: String should not be stretched too taut and the jerk should be as strong as possible

Q. Shyam was calculating the velocity of wave using a slinky. He asked his teacher about the features of spring to be used. Which of the following describes the features that the spring should have?

(a) Long, soft and flexible (b) Short, soft and flexible

(c) Short, hard and flexible (d) Long, soft but not flexible

Ans: (a) Long, soft and flexible

Q. If the time period of small ripples on water is 0.1sec.and their wave length is 6 cm. Find the speed of the ripple

Ans: Time period of ripple, T = 0.1 s ; Wavelength of the ripple, λ = 6 cm = 0.06 m

Frequency, f = 1/T = 1/0.1 = 10 hz ; Therefore, the speed of the ripple, v = fλ = 10×0.06 = 0.6 m/ s

Q. Why is it easier to swim in sea water than in river water?

Ans: Since, sea water has some salts in it, which results in increase in its density. And we know that buoyant force is directly proportional to density of liquid. As the result the swimmer experience the greater force upwards letting him to swim easily

Q. What are the differences between monocots and dicots?

Ans: Monocotyledonous plant have parallel venation whereas Dicot plant have reticulated venation

Q. Which adoptive feature found in earthworm keeps its skin always moist?

The body wall of earthworm has a moist secretion called mucus that makes the skin slippery and moist

Q. After setting up slinky for experiment to find velocity of pulse, how will you generate pulse :

Ans: By jerking Vertically Upward

Q. Flowers in dicotyledonous plants are generally:

Ans: pentamerous (floral parts in the number of fives).

Q. What is the source of nutrition of larvae of mosquito?

Ans: Larvae of mosquito feed on algae, bacteria and other microorganisms present in their surroundings

Q. Write two main precautions to be taken to read the water level in the graduated cylinder?

Ans: (i) Always note reading of lower meniscus of water level.
(ii) The reading has to be taken at the same level as that of the eye to prevent any parallex error.

Q. A student is performing the experiment 'To determine the density of solid (denser than water), by using spring balance and measuring cylinder'. During the experiment, he observed that a few air bubbles were sticking to the solid when immersed in water. What will the presence of air bubbles lead to?

(a) No change in density. (b) Increase in density. (c) Decrease in density. (d) None of these.

Ans: (c) Decrease in density because presence of air bubbles will increase the volume of displaced water.

Q. You are given solid cubes of Aluminium and Iron, each of side 4 cm and two spring balances. Balance A has a range of 0 to 250 g and a least count of 2.5 g, while balance B has a range of 0 to 1000 g and a least count of 10g. Which balance would be the preferred option for mass measurement of the cubes?

(a) Balance A for both the cubes.                 (b) Balance B for both the cubes.

(c) Balance A for the Aluminium cube and balance B for Iron cube.

(d) Balance A for the iron cube and balance B for aluminium cube.

Ans: (c) Balance A for the Aluminium cube and balance B for Iron cube. [because Density of iron is greater than Aluminium.]

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