Water fountains work due to the pressure exerted by water on the walls of the fountain pipe. It further depends on the force by which water enters the pipe.

The areas that are reserved for the wildlife, where they can freely use the habitats and natural resources are called National Parks.

The middle zone of a flame is yellow coloured because in this part amount of oxygen is less due to which unburnt carbon particles burn with yellow flame.

Natural gas is a fossil fuel, that is stored under high pressure as compressed natural gas (CNG). It is also used as a starting material for the manufacture of a number of chemicals and fertilisers.

Weedicides kill weeds while pesticides kill pests. Both are useful for the production of crops, but they are harmful in its use for farmers.

No, because friction depends on the nature of surface in contact.

The surface area of sharp knife is lesser than that of blunt knife. So pressure applied by sharp knife is higher than blunt knife.

Yes, when two forces of equal magnitude act in opposite direction, the net force is zero on that body.

The substance which provides heat and light is called fuels

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.

A flame has three zones in it:
(a) The outermost thin transparent faint bluish non-luminous region of complete combustion. It is the hottest zone of the flame.
(b) The middle bright luminous zone of partial combustion. It is the moderately hot zone. .
(c) The innermost, coldest dark zone, consists of hot vapour and is called zone of no combustion.
Blue zone near the bottom of the flame is due to burning of carbon monoxide. CO is formed due to incomplete combustion.

When an animal is killed illegally, it is called poaching. It usually occurs when an animal possesses something that is considered valuable.
Effect of Poaching on environment : The whole ecosystem is affected due to harm caused on animal population. Everything from the animals to the plants and even the people in a specific place is negatively affected. We need various species of flora and fauna in our environmental ecosystem so that it is balanced and healthy. Our own survival depends on it.
Effect of Poaching on humans : Two serious problems are faced by humans, first is spread of food-borne illnesses e.g., Ebola and anthrax and second major affect is depletion of natural resources.

(a) A is petroleum and B is natural gas.
(b) A is thick liquid while B is gas.
(c) C is called fractional distillation
(d) D is kerosene.

(a) Paddy is cultivated in rainy season as it is a kharif crop.
(b) For sowing paddy, seeds are first grown in a nursery and later seedling are transplanted in the field. This allows us to select only healthy and better seedlings for cultivation.
(c) Measures taken to prevent spoilage or damage of harvested crops from insect attack are:
(i) Exposing them in sunlight for drying as freshly harvested crops have moisture.
(ii) Dried neem leaves are added to stored grains, so as to prevent damage from pests.
(iii) Specific chemical treatments are also available for preventing crops.

The roots of the plants bind the soil particles and in the absence of trees, the level of ground water reduces. In the absence of tree cover, the seepage of water is reduced and ground water does not get replenished, thus deforestation leads to a decrease in water holding capacity of the soil.

Some microorganisms like bacteria, fungi or even some worms decompose, i.e., breakdown the dead leaves, animal remains and wastes into simple compounds and form carbon, nitrogen and other chemicals. Such microorganisms are called decomposers.

(i) The symptoms observed in the villagers show that oxides of nitrogen and sulphur must be coming out of the chimney. This is due to the combustion of fossil fuels like coal, oil, natural gas etc. to produce high temperature at which oxidation of atmospheric nitrogen takes place.
(ii) Sheela is aware, helpful and intelligent woman.

Types of combustion: It is of three types:
(i) Rapid combustion: When gases burn rapidly to produce heat and light, it is called rapid combustion.
(ii) Spontaneous combustion: When material suddenly bursts into flame, without the application of any apparent cause, it is called spontaneous combustion.
(iii) Explosion: When combustion takes place with sudden release of heat, sound, light and gas with a bang it is called explosion.

Burning of coal and diesel releases sulphur dioxide gas. It is an extremely suffocating and corrosive gas. Moreover, petrol engines give off gaseous oxides of nitrogen. Oxides of sulphur and nitrogen dissolve in rain water and form acids. Such rain is called acid rain.

Differences between fertilizer and manure:

It is due to continuous rubbing of soles with the ground, the spikes on the sole get damaged slowly and the soles become Slippery.

When the goalkeeper tried to grab the ball coming towards him, the force he applied caused it to change direction. At the same time, the force caused the ball to decrease in its speed. The force applied did not stop the ball from moving or increasing its speed.

Oil is lighter than water, hence floats over it.