Which one of the following statements about fertilizers is not correct?
- A.Urea is a phosphorus-containing fertilizer.
- B.Application of fertilizer to the soil increases fertility of the soil.
- C.Urea can be prepared by action of ammonia and carbon dioxide under high pressure and at high temperature.
- D.Urea contains more nitrogen than other fertilizers.
Correct answer
Explanation
The correct answer is A. Urea, CO(NH₂)₂, contains carbon, oxygen, nitrogen and hydrogen; it has no phosphorus at all and is a nitrogenous fertilizer.
Urea carries about 46% nitrogen, the highest of the common solid fertilizers, which is why it is the most widely used fertilizer in India. It is made industrially by reacting ammonia with carbon dioxide under high pressure and temperature. Phosphorus comes from fertilizers such as single superphosphate and diammonium phosphate (DAP), and potassium from muriate of potash.
B is correct as a statement because fertilizers add the nutrients the soil lacks and so raise its fertility.
C is correct as a statement because ammonia and carbon dioxide are the raw materials of urea plants.
D is correct as a statement because urea's 46% nitrogen is more than ammonium sulphate (about 21%) or calcium ammonium nitrate (about 25%).
Exam tip: N-P-K: urea for nitrogen (46%), superphosphate and DAP for phosphorus, muriate of potash for potassium.
Practice Questions
View allMarginal placentation, in which the ovules are borne along the fused margin of a single carpel, is found in
- A.Tomato
- B.Pea
- C.Mustard
- D.Sunflower
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The pea's ovary is made of one carpel whose two margins fuse to form a ridge, and the ovules are arranged in two rows along that ridge; this is marginal placentation, and it is why the pod opens to show a single row of seeds on each side.
Read the full explanation →Mango and coconut are examples of which type of fruit?
- A.Berry
- B.Drupe
- C.Pome
- D.Legume
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A drupe is a fleshy fruit with a thin epicarp, a mesocarp that may be pulpy as in the mango or fibrous as in the coconut, and a hard, stony endocarp enclosing a single seed; the coconut's shell is that endocarp and the white kernel is the seed.
Read the full explanation →The apple is regarded as a false fruit because
- A.It has no seeds
- B.It develops from the thalamus along with the ovary
- C.It develops without fertilisation
- D.Its pericarp is stony
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A true fruit forms from the ovary alone, but in the apple and the pear the thalamus grows, becomes fleshy and forms the greater part of the edible tissue, while the ovary makes only the core; such a fruit is called a false or spurious fruit, and the specific type…
Read the full explanation →Vexillary aestivation of the corolla is found in the flower of
- A.Pea
- B.Cotton
- C.Calotropis
- D.Gulmohar
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In vexillary or papilionaceous aestivation the corolla has five petals of unequal size: one large posterior petal, the standard, which covers two lateral wing petals, which in turn cover the two smallest anterior petals that are fused into a keel.
Read the full explanation →In a racemose inflorescence, the flowers are borne in
- A.Basipetal succession
- B.Acropetal succession
- C.A single terminal cluster
- D.No definite order
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In a racemose inflorescence the main axis does not end in a flower but keeps growing, so the lowest flower is the oldest and the youngest buds are at the tip; this upward order is called acropetal, as in radish, mustard and Larkspur.
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