(i) The person was spraying chemicals called weedicides on his crops to kill unwanted plants (weeds) in his field.
(ii)The mouth of the person was covered to prevent the inhaling of poisonous weedicides.
(iii) Ramu is attentive, observant, cautious and an intelligent boy.

Disadvantages of fertilizers:
(i) They become source of water pollution.
(ii) They make soil less fertile.
(iii) They do not provide any humus to the soil.

If despite favourable climatic conditions, farmer's crop failed to give good yield, the possibilities may be
(i) he did not use good quality and healthy seeds.
(ii) his field was not well irrigated.
(iii) manures/fertilisers were not timely and properly applied.
(iv) weeds were not removed.
(v) seeds were not sown at appropriate distance.
(vi) the soil was not ploughed and levelled properly.

From the above given crop list, the kharif and rabi crops can be grouped as

Threshing - The process in which the grain seeds are separated from chaff is called
threshing. This is carried out with the help of a machine called combine that is a combination of a harvester and thresher.

Farmers can increase the fertility of the soil by :
(i) adding manure and fertilizers.
(ii) crop rotation.
(iii) leaving the field uncultivated in between two crops.

Yes, sprayer of weedicide may affect the health of farmers.

Ploughing of the soil during soil preparation creates aeration and loosen the soil which promotes earthworms and microbes to grow and release nutrients in soil.

The process of providing manure to replenish the soil with nutrients is called manuring.

Seed drill is an odd pair in the above given set of tools as it is a modern agricultural tool used to sow seeds at uniform distances and to properly cover them with soil.

Main tools used to prepare soil are as follows:
(i) Plough: This implement is made of wood and is drawn by a pair of bulls or other animals. It is used for tilling the soil, adding manure, removing the weeds, scraping of soil etc.
(ii) Hoe: It is a simple tool that is used for removing weeds and for loosening the soil.
(iii) Cultivator: Ploughing is done by tractor-driven cultivator. It uses less labour and time.

Besides the given tools, the other items required for raising a garden are seeds and seedling of vegetables, plants from nursery, kitchen waste, manure, water, soil.
Steps for raising the garden:
(i) Kitchen waste will be collected and composted in a pit.
(ii) A patch of land will be identified for the garden.
(iii) Soil will be dug up and levelled with the help of a spade.
(iv) Sowing of seeds/ transplanting of seedlings will be done.
(v) Select seeds/seedlings as per the season. Water the plants regularly with a water-can
(vi) Compost will be applied.
(vii) Weeds will be removed periodically with the help of khurpi.

The ability of soil to supply all the essential plant nutrients to a crop in adequate quantity is called soil fertility. Repeated growing of crops in the same soil removes various nutrient elements from the soil due to which the soil loses its fertility.
The soil fertility can be replenished or regained by the following methods:
(i) By keeping the field fallow (uncultivated) for one or two seasons.
(ii) By putting manures and fertilisers in the soil.
(iii) By practising crop rotation .
(iv) By practising multiple cropping (mixed cropping).