Scientific Reasons From Past Papers
➽ Australian continent has winter season when we have summer season in Pakistan.
Ans: the earth on its axis is not at a vertical angle to its orbit. It is inclined at an angle of about. In this way when the northern hemisphere of the earth is inclined to the sun and getting direct sun rays, southern hemisphere is inclined away from the sun and getting less direct rays. Thus the northern hemisphere has summer season and southern hemisphere has winter season. Pakistan is in the northern hemisphere while Australia is in the southern hemisphere. So when there is winter in Australia there is summer season in Pakistan.
➽ Meat takes longer to cook on mountains.
Ans: The meat takes longer time to cook on the mountains because the atmospheric pressure decreases with attitude and the boiling point of a liquid is directly proportional to the atmospheric pressure.
➽ Water remains cool in earthen pitcher.
Ans: This occurs due to the process of evaporation. Water gets cooled on evaporation. As the earthenware pitcher is concerned, they have small pores. Water tends to come out of pores and evaporates which results in cooling effect on the earthenware and water. While in the metal pots there are no pores and evaporation does not take place. Besides metal has tendency to absorb heat that why water does not get cooled in a metal pot
➽ Ice and salt mixture is used as a freezing agent by manual ice-cream makers.
Ans: In manual ice-cream making a mixture of salt and ice is always used because salt has capacity to reduce the temperature of ice by decreasing its freezing point. That’s why ice and salt mixture is used as freezing agent in manual ice cream making.
➽ It is not advisable to sleep under trees during the night.
Ans: During night the plants release carbon dioxide (CO2) which is a poisonous gas and injurious to health. That is why it is not advisable to sleep under trees during night.
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