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CBSE Class 9 Science Solved Practice Paper SA-II, 2017: Set-XII

Feb 7, 2017 18:56 IST

Jagranjosh.com, India’s leading education portal, presents CBSE Class 9 Science Solved Practice Paper for Sumamtive Assessment-II, 2017. Subject experts, after the concise analysis of previous years’ papers, latest CBSE syllabus and pattern, have designed this paper which represents a collection of the important questions that might be asked in the upcoming exams. This paper will surely help the students in understanding the depth with which a topic should be studied in order to prepare in a more effective way to get the desired results.

CBSE Class 9 Mathematics Solved Practice Paper SA-II, 2017

Some sample question from the paper are:

Q. Why is the skin of amphibians moist?

Ans. The moist of amphibians aids the respiratory functions  by the passage of substances such as oxygen and water.

Q. Give reason for the following:

(a) Nucleus of an atom is charged

(b) Noble gases show low reactivity.

(c) An atom is electrically neutral.

Ans.

(a) The nucleus of an atom is composed of protons and neutrons out of which neutrons have no charge whereas protons are positively charged, which makes the nucleus to have an overall positive charge.

(b) Noble gases have completely filled orbitals / energy levels due to which they find it difficult to gain or lose the electrons so as to combine with some other atom to form a compound. That is why noble gases show low or negligible reactivity.

(c) An atoms is electrically neutral because it consists of equal number of protons (positively charged) and electrons (negatively charged).

Q. Tabulate three differences between acute and chronic diseases.

Ans.

Differences between acute and chronic diseases are:

 Acute Diseases Chronic Diseases 1. Lasts for only very short periods of time. Example: common cold 1. Lasts for a Long time, even as much as life time. Example: ELephantiasis. 2. The patient recovers completely after cure. 2. Chronic health conditions may last for the rest of one’s life. 3. There is no weight loss or tiredness afterwards. 4. There is often weight loss or feeling of tiredness.

Q. (a) List any two benefits of classification.

(b) Why bryophytes and pteridophytes grow in moist and shady places?

Ans.

(a) Two benefits of classification are:

(i) It makes the study of living organisms convenient.

(ii) It helps in the specific identification of any given organism.

(b) Pteridophytes and bryophytes grow in moist and shady places due to the following three reasons.

(i) Unlike the terrestrial plants, pteridophytes and bryophytes have thin and delicate cuticle and stem which can cause excess water loss. Hence staying in shade helps conserve water.

(ii) Ferns and mosses, being the most common examples of pteridophytes and bryophytes, usually reproduce through spores rather than seeds. The spores require moisture for their next stage of growth.

(iii) Delicate tissues of ferns and mosses can easily get damaged by the continuous exposure to sunlight.Hence growing in shade protects the tissues from damaging due to the heat of sun.

Q. What is reverberation? How can it be reduced? Give two applications of reflection of sound wave.

Ans.

Reverberation: The repeated multiple reflections of sound in any big enclosed space is known as reverberation. A large number of echoes so formed overlap with original sound due to which sound seems to be prolonged and lasts for a longer time.

The reverberation can be reduced by covering the ceiling and walls of the enclosed space with sound absorbing materials, such as fibre board, loose woollens, curtains, etc.

Two applications of reflection of sound are:

(i) Stethescope: Stethescope is a device in which the sound travels with the multiple reflection inside its column and reaches to the listeners ear.

(ii) Sound boards: Curved surfaces can reflect sound waves. This reflection of sound waves is used in auditorium to spread the waves uniformly throughout the hall. The speaker is located at the focus of the sound board.

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