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Read the given passage and select the correct option for the following questions. The sound returning back towards the source after suffering reflection from a distant obstacle like wall, hill etc. is called an echo. A cracker is fired by a child. The child hears an echo from a cliff 4 seconds after the sound produced by a cracker. The speed of sound in air at 20°C is 344 m s^-1.
What is the minimum distance between the observer and the obstacle for echo to be heard?

A17.2 m
B15.2 m
C14.2 m
D34.4 m

Study the given table.

Select the option that correctly identifies any two of them.

A P – Rubber, R – Copper
B Q – Aluminium, R – Wood
C P – Wood, Q – Iron
D Q – Iron, R – Glass

Observe the given flow chart carefully and answer given Q.

What does Z indicate?

A Red litmus does not show change in colour
B Red litmus turns blue
C Red litmus turns yellow
D The solution becomes colourless

Which process is used in the given figure to remove impurities from water?



ASedimentation
BFiltration
CDistillation
DDecantation

Two men, A and B, are facing a flat and hard wall as shown in the given figure. When man A makes a clap, man B hears two claps. The speed of sound in air is 320 m s^-1. What is the interval between the two claps heard by man B?



A2.14 s
B2.78 s
C3.16 s
D3.75 s

converts

AMechanical energy into electrical energy
BSolar energy into electrical energy
CChemical energy into sound energy
DGeothermal energy into heat energy

If earthquakes occur then it may cause
I. Tsunami II. Floods
III. Landslides

AI only
BII only
CI and III only
DI, II and III

Read the given passage and answer the following questions.
An unidentified flying object (UFO) lands on a planet at a point 5 kilometres from an active volcano. Just after the landing, a volcanic eruption occurs. The time interval between the flash of light from the volcanic explosion and the sound of eruption was registered as 100 s. The time period of the sound waves produced is 2 s.
Which of the following is carried by waves from one place to another?

AMatter
BMatter and Energy
CWavelength
DEnergy

Study the given Venn diagram and select the option that correctly identifies X.


AKalpana Chawla
BNeil Armstrong
CRakesh Sharma
DSunita Williams

In a plant, smooth seeds (S) are dominant over wrinkled seeds (s) and green seeds (G) are dominant over yellow seeds (g). A plant homozygous for smooth and green seeds is crossed with a plant having wrinkled and yellow seeds. The F₁ offsprings are self crossed to produce F₂ generation. If a total of 160 offsprings are produced, how many plants are expected to be having wrinkled and green seeds in F₂ generation, according to a typical Mendelian cross?

A 90
B 30
C 20
D 10