Last seen: Nov 14, 2021
The four methods of weed control are as follows: Mechanical methods: These include the following methods : uprooting, weeding with trowel or ‘khurp...
(a) Examples of narrow-leaved Rabi season weed: Mandoosi (Phalaris) and wild oat or jungali jaii. (b) Examples of broad-leaved Kharif season weed: ...
Infestation of different types of insect pests can be controlled by the following methods : Root cutting types of insects are controlled by mixin...
Following are the three ways in which an insect pest can attack the crop plants: 1. Chewing insects: They destroy all kinds of crop plants by cutti...
Depending upon the occurrence and transmission, plant diseases are classified into four categories: (i) Seed-borne diseases: These diseases spread ...
Biological methods of weed control are described below: Introducing the insects or some other organisms in the field that specifically consumes a...
Plant breeding is the process of producing new varieties of plants by artificial selection. It is a method of improving the genetic make-up of plants....
Correct answer: (d) CrO2Cl2 Explanation: CrO2Cl2 Let O No. of Cr = x ∴ x + 2 (–2) + 2 (–1) = 0 x – 4 – 2 = 0 ∴ x = + 6
Correct answer: (c) 16 Explanation: SO2 is an oxidising agent 4e- + SO2 → S Equivalent of SO2 = = 16
Correct answer: (d) Mg3N2 → –3 Explanation: (a) +3 + 5x + 15 - 1 = +2 5x + 17 = +2 5x = -15 x = –3; Oxidation State of N = -3 (b) NH...
Answer: (c) +3 Explanation: O.N. of N changes from -2 to +3.
Correct answer: (b) (i) and (iv) Explanation: Oxidation reaction (loss of 2e–) 2Na(s) + S(s) → Na2S(s) Na (x) → Na2 Oxidation reaction (loss ...
Correct answer: (c) I- will be oxidised to I2 Explanation: Given Fe3+/Fe2+ = + 0.77 V and I2 /2I- = 0.536V 2(e- + Fe3+ → Fe2+) E° = 0.77 V ...
Steps of hybridisation are explained below: (i) Varieties of plant with desirable characters are selected. These plants are genetically dissimilar....
Leguminous crops are desirable in crop rotation because they maintain the supply of nitrogen in the crop fields. These crops are alternated with other...
The main criteria for selecting crops for rotation are as follows: Availability of moisture through rain or irrigation. Status of nutrients in t...
Disadvantages of crop rotation are as follows: (i) It is more concerned about the need of the soil and not of the crops. (ii) It may lead to low...
Intercropping is a method of growing two or more crops simultaneously in a definite pattern of rows in the same field. Its main aim is to increase the...
Following are the advantages of mixed cropping: It reduces the risk of crop failure due to environmental stress. Pest infestation of crops is g...
Mixed Cropping: Its aim is to reduce the risk of crop failure. Seeds of the selected crops are mixed together before sowing. Applying fertiliser...