13 Select the correct answer.
A farmer changed certain timings of his farming operations to control pest infestation in his field. Which pest control method did he use?
OA.
genetic pest control
OB.
biological pest control
C.
cultural pest control
D.
chemical pest control
OE.
mechanical pest control

Cultural Pest Control.

Explanation:

The cultural pest control is one of the oldest methos of pest control. This form of pest control is less practiced these days since curative form of pest control methods have been invented. The cultural pest control method is a preventive method of managing pest population. This pest control method takes long days of planning and execution.

In this form of pest control method, the farmer had to change the timings of his farming operations in his field. This method requires careful timing in seeding and planting. This method of pest controlling requires knowledge and skills of fields.

Thus the correct answer is the third option.

- calcium has greater affinity to bond with electron receptors than hydrogen does and hence, it has the ability to replace hydrogen in most of its compounds.

- lithium has 2 valence electrons in the product because it can make only 1 bond with hydrogen. beryllium has 4 valence electrons in the product because it can only make 2 bonds. it has fewer electrons than neon and can react with electron donors. each hydrogen has 2 valence electrons, the same as helium.

- the covalent bond formed between carbon and hydrogen is polar because carbon is more electronegative than hydrogen and it attracts the bonded electron pair closer to itself, thus giving hydrogen a partial positive charge.

- a hydrogen bond is a relatively weak bond that hydrogen atoms make with the electronegative atoms nitrogen, oxygen or fluorine.

so the best choice is a.) 2 calcium (ca) atoms