Q: Which one of the following gases, present in the air near the surface of the Earth, has maximum concentrations?

A: Oxygen

B: Hydrogen

C: Nitrogen

D: Methane



Correct Option: C  [ Nitrogen ]

Remark:


Q: Helium is preferred to hydrogen in air balloons because it:

A: is cheaper

B: is less dense

C: has greater lifting power

D: does not form an explosive mixture with air



Correct Option: D  [ does not form an explosive mixture with air ]

Remark:


Q: The digested food is absorbed in

A: Stomach

B: Intestine (small)

C: Intestine (large)

D: Colon



Correct Option: B  [ Intestine (small) ]

Remark:

Explanation: The small intestine is the primary site of absorption of digested food. Its inner lining has numerous tiny finger-like projections called villi and microvilli that greatly increase the surface area for absorption. Nutrients such as glucose, amino acids, fatty acids, vitamins, and minerals pass into the blood and lymph through these structures. The large intestine mainly absorbs water and fo


Q: Heavy water is :

A: Ice

B: Water at 4 degree Celsius

C: Deuterium oxide

D: Solution of sugar and water



Correct Option: C  [ Deuterium oxide ]

Remark:

Explanation: Heavy water is chemically known as Deuterium oxide (D₂O). It is similar to ordinary water (H₂O), but the hydrogen atoms are replaced by deuterium — a heavier isotope of hydrogen containing one proton and one neutron. Heavy water is not suitable for drinking but is used as a moderator and coolant in nuclear reactors because it slows down neutrons, allowing a controlled nuclear fission reaction. It is also used in scientific research and isotope studies.


Q: Tetraethyl lead (TEL) is

A: a catalyst used in burning fossil fuel

B: an antioxidant

C: a reductant

D: an antiknock compound



Correct Option: D  [ an antiknock compound ]

Remark:


Q: The hottest part of the gas flame is known as:

A: luminous zone

B: dark zone

C: blue zone

D: non-luminous zone



Correct Option: D  [ non-luminous zone ]

Remark:


Q: Check the odd term out:

A: Internet

B: Linux

C: Unix

D: Windows



Correct Option: A  [ Internet ]

Remark:

Explanation: Internet is the odd one out because it is a global network, whereas Linux, Unix and Windows are operating systems.


Q: In your opinion which of the following is due to ozone hole ?

A: Increased UV radiation

B: Acid rain

C: Global warming

D: Greenhouse effect



Correct Option: A  [ Increased UV radiation ]

Remark:

The ozone hole leads to an increase in ultraviolet (UV) radiation reaching the Earth's surface. The depletion of the ozone layer, caused by chemicals like CFCs (chlorofluorocarbons), reduces its ability to block harmful UV rays. This can result in health issues such as skin cancer, cataracts, and also harm to crops and marine ecosystems.

  • Acid rain: Caused by sulphur and nitrogen oxides, not ozone depletion.
  • Global warming: Caused by greenhouse gases trapping heat.
  • Greenhouse effect: Natural process intensified by CO₂, not related to ozone loss.


Q: What is the first artificial satellite to orbit Earth ?

A: Sputnik I

B: Explorer I

C: Vanguard I

D: Discoverer I



Correct Option: A  [ Sputnik I ]

Remark:

Sputnik I was the first artificial satellite to orbit the Earth. It was launched by the Soviet Union on October 4, 1957. The successful launch of Sputnik I marked the beginning of the space age and initiated the space race between the USA and the USSR.

  • Explorer I: First U.S. satellite, launched in 1958.
  • Vanguard I: A U.S. satellite launched later in 1958.
  • Discoverer I: Part of an American reconnaissance satellite program (1959).


Q: Xylem helps in transportation of which of the following?

A: food

B: water

C: nutrient

D: both food and water



Correct Option: B  [ water ]

Remark:

Xylem is a type of vascular tissue in plants responsible for the transportation of water and dissolved minerals from the roots to the stems and leaves. The upward movement of water through xylem vessels occurs due to processes like transpiration pull, root pressure, and capillary action. Xylem also provides mechanical support to the plant.

Other options (for context)

  • Food: Transported by phloem, not xylem.
  • Nutrient: Minerals are carried along with water but the primary function of xylem is water transport.
  • Both food and water: Incorrect — only phloem transports food; xylem transports water.
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