National Science Olympiad Model Paper 1 Questions and Answers Part 11

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Q. 44. Match Column-1 with Column- II and select the correct answer using the codes given below.

Match Column-1 with Column- II and Select the Correct Answer Using the Codes Given Below
Column-IColumn-II
1Nitrous oxideI.Secondary pollutant
2ChlorofluorocarbonII.Combustion of fossil fuels,
3MethaneIII.Denitrification
4Ozone (O3)IV.Refrigerators
5Carbon dioxideV.Cattle, rice field, toilets.

A) 1-III; 2- IV; 3- V; 4- I; 5-II

B) 1-V; 2- I; 3- III; 4-IV; 5- II

C) 1-IV; 2-V; 3-I; 4-II; 5-III

D) 1 - 1; 2-III; 3-IV; 4-V; 5-II

Answer: A

Explanation:

1. Denitrification: The loss or removal of nitrogen or nitrogen compounds specifically: reduction of nitrates or nitrites commonly by bacteria (as in soil) that usually results in the escape of nitrogen into the air

2. Chlourofluoro carbon is used in refrigeration for e. g. Freon 6

3. Residue of Cattle, rice field, toilets releases Methane gas

4. Ozone situated in troposphere is considered as secondary pollutant

5. Combustion of fossil fuel lead to emission of carbon dioxide as it contains carbon and on burning in presence of oxygen it releases carbon dioxide.

Q. 45. Choose the correct pair

Arthropoda – Centipedes

Pisces-Lob stern

Mollusca-Millipedes

Annelids- Crabs

Answer: A

Explanation:

a) It is correct pairs as all are explains of arthropod as they have segmented bodies, bilateral symmetry.

b) It is incorrect pair as Pisces are aquatic vertebrates that live in water

c) Its incorrect pair as mollusc are triploblastic , in which three layers body is covered by mantle

d) Annelids contains fluid filled cavity referred to as coelom which is not present in crabs.

Achiever section

Q. 46. Given Below is the graph of a body whose initial velocity is v0. The body travels through a straight line with acceleration as shown in the graph. Determine the maximum velocity of the body.

Given below is the Graph

A)

B)

C)

D)

Answer: D

Explanation:

Area under the Curve

Acceleration: Area under the curve

=

a = =

Putting the value of a we get,

Q. 47. Statement: Sound from a tuning fork is louder when its stem is placed on a desktop

Reason: When a wave reaches another denser medium some part of it is reflected

A) Both Statement and Reason are correct, and Reason is the correct explanation for Statement.

B) Both Statement and Reason are correct, but Reason is not the correct explanation for Statement.

C) Statement is correct, but Reason is incorrect.

D) Both Statement and Reason are incorrect.

Answer: C

Sound from a Tuning Fork

Explanation: When the prongs of tuning fork held in the hand are struck by a hammer, they start vibrating and set the nearby air molecules into a vibration mode. The sound is very soft and barely audible. When the stem is put on the desktop, the desktop start vibrating with the same natural frequency as that of the tuning fork, forcing the surrounding air molecules to vibrate with the same frequency. Being of a large size, the desktop sets larger number of air molecules in vibrations.

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