[جيهان أبو شعيشع]

3 Justify:
a) Although oxygen is consumed during respiration, its percentage remains stable in the atmosphere. بالرغم من استهلاك الاكسجين خلال عملية التنفس إلا أن نسبته تبقى ثابتة فى الجو
Because of the sustainability ofphotosynthesis. بسبب بقاء عملية البناء الضوئي
b) Oxygen is created by displacing the water downward in the flask during preparation at the laboratory.
Because it doesn’t dissolve in water.لانه لا ينحل بالماء ( مذكورة فى خصائص الأكسجين)
على عكس ثانى أكسيد الكربون الذى ينحل بالماء لذلك عند تحضيره لا نستخدم الماء فى المخبار لاحظ الفرق على الرسم الخاص بتحضير كل غاز


c) The atmosphere has a great importance for the continuity of life on the planet.
Because it protects the Earth by absorbing ultraviolet radiation coming from outer space.




3) Justify:
a) Clear limewater is used to detect the presence carbon dioxide.

ماء الجير هو هيدروكسيد الكالسيوم ( أكسيد كالسيوم مذاب فى الماء)

وقلنا قبل كدة أن ثاني اكسيد الكربون ينحل بالماء ، لذلك عندما يمر على هيدروكسيد الكالسيوم يحدث تفاعل يعكر ماء الجير

Because it turbids limewater.
b) Carbon dioxide is used in extinguishing fires.
Because It does not burn and does not help in combustion.
c) Carbon dioxide has a great importance for the continuity of life on Earth.
Because it contributes يدخل فى in the photosynthesis process in green plants.
a) Nitrogen is recently used in filling car tires.
To get it relative constancy الثبات النسبي of its volume at the change of temperature.
b) Liquefied nitrogen is used for cooling food products and medicines.
Because it is changing into gas directly when the temperature increases. So it doesn’t make damage to food or medicine
c) The main source of nitrogen is the air.
Because it presents 78% of the Earth’s atmosphere.
d) We prepare nitrogen by passing air across the sodium hydroxide or potassium.
To absorb small amounts of carbon
dioxide from the air.
e) Nitrogen contributes in the composition of all living tissues.
It is a main component in all proteins.
f) Nitrogen is used to store petroleum and some flammable materials.
It is used as an inactive material