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Weather is the condition of the atmosphere over a short period of time, whereas climate is the weather pattern of a place over a long period of time. Hence weather changes frequently.

Answer: Option B. -> humidity
:
B
The amount of moisture present in the air is termed humidity. Humidityindicates the likelihood of precipitation, dew or fog.​​ Drought is the long term shortage of water which makes life difficult.

Answer: Option C. -> weather
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C
Weatheris defined as the atmospheric conditions of a specific place over a short interval of time. Whereas, climate is a long term pattern of weather changes in an area.

Answer: Option C. -> migration
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C
Birds need warm weather for survival. When the climate turns cold, birds fly away in groups to places with warmer climates which is suitable for their survival. This phenomenon is called migration. The birds return to their homes when the climate becomes favourable for them.

Answer: Option A. -> desert
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A
The region which receives very little rainfall is called a desert.The lack of precipitation makes the region quitehostile for normal plant and animal life. Tropical rain forests get the maximum rainfall.

Answer: Option A. -> Sun
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A
Sun is the central ball of fire around which all planets move. Theweather conditions on earthchange depending on the amount of sunlight reaching the earth. The tilt of Earth’s axis relative to its orbit around the Sun results inchanges in the duration of daylight and the amount of sunlight received at any place throughout the year. These changes cause the annual cycle of seasons.Therefore, weexperience different weather conditions.​

Answer: Option D. -> Rain gauge
:
D
$\bullet$ Rain gauge isan instrumentthat is used for collecting and measuring rainfall.
$\bullet$ Thermometreis an instrument that is used to measure temperature.
$\bullet$ Barometreis an instrument which is used to measure the air pressure.
$\bullet$ Anemometreisan instrument that is used for measuring wind speed.

:
Each point: 1Mark
(a) Weather is the daily fluctuation in temperature, humidity, etc., while climate is the average weather pattern of a place.
(b) Humidity indicates the wetness of a place due to the amount of moisture in the atmosphere while rainfall is the drops of water that fall from clouds on the ground.
(c) Polar region remains very cold for most part of the year whereas tropical rainforest has a hot and humid climate.

:
Definition: 1 Mark
Instrument: 1 Mark
Humidity is a measure of the moisture in air.
Hygrometer is the instrument used to measure humidity.

:
Each adaptation and explanation: 1 Mark
1.Structural adaptations - These are special body parts of an organism that help them to survive in theirnaturalhabitat (e.g., skin colour, shape, and body covering).
2.Behavioural adaptations - These are special ways in which a particular organism behaves to survive in its natural habitat.A behavioral adaptation is an action that animals carry out to increase their chances of survival and reproduction.
3.Physiological adaptations - These are internal systematic responses to external stimuli in order to help an organism maintain homeostasis.