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Select the option which correctly identifies true (T) and false (F) statements.
(i) Ionosphere is a part of troposphere.
(ii) Smoke combines with oxygen to form smog, that affects visibility.
(iii) The ozone layer absorbs harmful UV rays of Sun.
(iv) Clouds, rain, fog and snow are all forms of water.
(v) Air exerts pressure in downward direction only.

Study the given Venn diagram and select the incorrect option regarding organs P, Q and R.


A P could be a sense organ that also helps in mixing of food with saliva in the mouth.
B Q could be an organ which churns the food so that it mixes with digestive juices and acid.
C P could be a sense organ that helps to take up atmospheric air and possesses hair which traps dust particles and germs.
D R could be an organ that pumps blood to all other body organs through blood vessels.

The population of animal P in a certain community was constant until a population of animal Q was subsequently introduce into that community. The interaction between the two populations is represented in the given graph. Which of the following can be inferred from the given graph?


A Q could be a carnivore who is the predator of P who could be a herbivore or a carnivore.
B P could be a herbivore who feeds on some specific plants whereas Q could be an omnivore who not only feeds on those specific plants but also feeds on P.
C Q could be an exotic animal species which competitively drove out the entire population of animal species which is the only prey of P.
D All of these

Which of the following statements about the circuit is/are incorrect?

I. Lamp L₁ will light up when either L₂ or L₃ are lighted.
II. Electricity will flow only when all the switches are closed.
III. Electricity will flow as long as any one switch is closed.

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

Read the given statements and select the correct option regarding them.
Statement 1: Digestion and blood circulation are some voluntary actions of our body.
Statement 2: Voluntary actions are the actions which are not under human control.

ABoth statements 1 and 2 are correct and statement 2 is the correct explanation of statement 1.
BBoth statements 1 and 2 are correct but statement 2 is not the correct explanation of statement 1.
CStatement 1 is true but statement 2 is false.
DBoth statements 1 and 2 are false.

Which of the following can be used as antacids to reduce acidity in stomach?

ASodium carbonate and magnesium hydroxide
BMagnesium hydroxide and sodium hydroxide
CSodium bicarbonate and calcium hydroxide
DSodium bicarbonate and magnesium hydroxide

The weight of an empty balloon on a spring balance is W₁. The weight becomes W₂ when the balloon is filled with air. Let the weight of the air itself be w. Neglect the thickness of the balloon when it is filled with air. Also neglect the difference in the densities of air inside and outside the balloon. Which one is correct?

AW₂ = W₁
BW₂ = W₁ + w
CW₂ > W₁
DNone of these

The lengths of the mercury thread in a thermometer immersed in pure melting ice and in pure boiling water are 8 cm and 24 cm respectively. What is the temperature of a liquid if the length of mercury thread is 16 cm in the liquid?

A50 K
B273 K
C323 K
D373 K

At room temperature the internal and external radii of a metal ring are r₁ and r₂ as shown in the figure. When the ring is heated at 100°C, then


Ar₁ decreases and r₂ decreases
Br₁ decreases and r₂ increases
Cr₁ increases and r₂ decreases
Dr₁ increases and r₂ increases.

Study the given graph. Identify gases X, Y and Z and select the correct statement.


AGas Y is used for respiration and extinguishing fire.
BAutotrophs use X and Z gases directly to prepare their food in the presence of sunlight.
CX does not help in burning of substance and is used in food packaging to keep the food fresh.
DNone of these