Which one of the following is not a nitrogen fertilizer ?
- A.(NH₄)₂SO₄
- B.NH₄NO₃
- C.N₂
- D.(NH₂)₂CO
Correct answer
Explanation
The correct answer is C, N₂. Nitrogen gas is the element itself in a very stable form, and plants cannot take it up directly from the soil or the air, so it is not used as a fertilizer.
A nitrogen fertilizer must supply nitrogen in a form that dissolves in soil water and reaches the roots as ammonium or nitrate ions. The two atoms of an N₂ molecule are held by a strong triple bond; only nitrogen-fixing bacteria such as Rhizobium in legume nodules, lightning, or the industrial Haber process can break it. Air is already about 78% nitrogen, yet crops still need fertilizer for this reason.
A, ammonium sulphate, is a common nitrogen fertilizer that also supplies sulphur. B, ammonium nitrate, gives nitrogen as both ammonium and nitrate. D, (NH₂)₂CO, is urea, the most widely used nitrogen fertilizer in India, with about 46% nitrogen.
Exam tip: urea 46% N is the richest solid nitrogen fertilizer; free N₂ must first be fixed before plants can use it.
Practice Questions
View allA negative work is done when an applied force F and the corresponding displacement S are
- A.perpendicular to each other.
- B.parallel to each other.
- C.anti-parallel to each other.
- D.equal in magnitude.
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Work is negative when the force acts opposite to the displacement, because the angle between them is then 180°. Work done is W = F S cos θ, where θ is the angle between the force and the displacement.
Read the full explanation →Which one of the following statements about a satellite orbiting around the Earth is correct ?
- A.Satellite is kept in orbit by remote control from ground station.
- B.Satellite is kept in orbit by retro-rocket and solar energy keeps it moving around the Earth.
- C.Satellite requires energy from solar panels and solid fuels for orbiting.
- D.Satellite does not require any energy for orbiting.
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Once a satellite is placed in orbit with the right speed, the Earth's gravity keeps it going round without any engine.
Read the full explanation →Which one of the following is not a conservative force ?
- A.Frictional force
- B.Electric force
- C.Gravitational force
- D.Spring force
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Friction is a non-conservative force because the work it does depends on the path taken and the energy it removes is lost as heat.
Read the full explanation →A microphone converts
- A.electrical signals to sound waves
- B.sound waves to electrical signals
- C.microwaves to sound waves
- D.sound waves to microwaves
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A microphone is a transducer that changes the pressure variations of sound into a matching electrical signal. In a common dynamic microphone, sound waves make a thin diaphragm vibrate.
Read the full explanation →When a light ray passes through from air to water with a non-zero angle the ray will be
- A.bending towards the normal
- B.bending away from the normal
- C.propagating in straight line
- D.reflected towards the opposite direction
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Light slows down when it enters water from air, so a ray that strikes the surface at an angle bends towards the normal.
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